With "Dawn of X," Jonathan Hickman and company are telling a larger story of a mutant utopia. However, there have been hiccups along the way. The outside world of humanity is skeptical of the mutants' motives. Some groups have even been actively plotting to stop Krakoa. Most importantly, there have been hints that not all the mutants on Krakoa are completely on board with the plan.
Many of Krakoa's Quiet Council are former enemies of the X-Men. Professor X's closest partner in the endeavor is someone that once was his sworn enemy. Some mutants have kept their secrets even after arriving on the island. Some may have their agenda. Some may be angry enough to betray an entire nation of mutants.
10 Doug Ramsey
Doug Ramsey may seem like an odd choice. On Krakoa, Doug Ramsey's powers allow him to be one of the few mutants capable of communicating with Krakoa. He's always been a friend to other mutants. However, his closest relationship was with an alien, the Technarch refugee known as Warlock. The two even managed to form of symbiosis before Doug Ramsey died the first time.
The Technarchy and the Phalanx are closely related. Technarchs like Warlock and his father Magus have been theorized to be advance scouts for the Phalanx. In Powers of X, audiences saw how the Phalanx may be destined to assimilate humanity and its incorporated AIs. If Doug Ramsey's Warlock is part of the Technarch scouting mission and not his old friend, audiences could be looking at trouble. If the Technarch is controlling Doug Ramsey to gain information for the Phalanx, then it could be disastrous.
9 Magneto
Magneto would be an odd choice to betray Krakoa. He has set himself up to be one of their greatest heroes. His recent defeat of a Coatai invasion seems to show that his experience as a ruthless proponent of mutant domination makes his allegiance unquestionable.
However, Magento has always been a leader. He's ill-suited to simply fall in line with another's goals. If Professor X or Moira MacTaggart were to demand his obedience, he could easily rebel. A more likely scenario might be if Magneto were overruled by the Quiet Council. Krakoa's greatest hero might turn into its devil.
8 Mister Sinister
Mister Sinister's genetic database is the basis of the resurrection protocols of the five. He has seemed harmless for the most part, indulging in gossip floating through Krakoan society. Unfortunately, this is the same man that sent a team of homicidal mutants out to exterminate the Morlocks.
Mister Sinister has taken as his charge several damaged mutants. Their first mission was to destroy one of his cloning labs, one that benefits Krakoa, but also benefits Mister Sinister, who held secrets from Psylocke, whom Cyclops put in place to lead his new Hellions. There's definitely a plan in place. What it is only time will tell.
7 Wolverine
While he has evolved and matured, Wolverine will always remain somewhat of a loose cannon. He's capable of killing in a moment. While he seems to be the perfect mutant to lead X-Force, it also means that he gets the jobs that the Quiet Council can't talk about.
What happens when he's given an assignment that he disagrees with? He's also proven capable of undermining the Quiet Council so he could stop the Pale Girl with Magneto's helmet. Could Logan be stopped if he decided that the Quiet Council had crossed a line? He certainly could cross them, and no-one would know until it was too late.
6 Moira MacTaggart
On the surface, Moira MacTaggart seems like the last person to betray Krakoa. However, she has seen this experiment go wrong before. In her fifth lifetime, she and Professor X created the mutant nation of Faraway. In her sixth timeline, something very similar to Krakoa took place, but with humans keeping mutants isolated to prevent them from interfering in humanity being absorbed by the Phalanx. Later efforts proved just as ineffective at preventing the fall of mutantkind.
Moira is keeping her existence secret from everyone but Magneto and Professor X. She hides in a blackout zone in Krakoa. She has steadfastly refused to allow precogs on the island, fearing that they, Destiny especially, would see the mutant Utopia plan as doomed. Perhaps her fatalistic worldview will drive her to stop deviation to her plan at all costs.
5 Professor X
Professor X has a position of superiority over all other mutants on Krakoa. While he makes no pronouncements to overthrow the Quiet Council, he does steer the discussions. With Magneto, and to a lesser extent Apocalypse, Professor X is the public face of Krakoa. His assassination has even been attempted by anti-mutant groups.
Professor X has deviated from Moira's plan, remaining optimistic about his more pacifist way of uniting mutants and humans. These plans have been sadly doomed to fail. Most egregiously, they have led to his transformation into Onslaught and his death at the hands of Cyclops and the Phoenix Force. Professor X does have a tendency to be overly optimistic and he could convince himself to betray Moira's plan.
4 Shinobi Shaw
Shinobi Shaw has a tendency to scheme for his best interests. He is also willing to betray anyone to get ahead. His debut saw him apparently murder his own father. Even his allies have proven expendable when they cease being of use to him. His role as Sebastian Shaw's Black Bishop is planned to be temporary until Kate Pryde can be eliminated as the Red Queen.
The problem is that Shinobi took time out of being introduced to the new world of the Hellfire Trading Company to visit the Yakuza. He has a debt to Japanese organized crime and may be more loyal to them than he is to his father. If it means clearing his debt to the Yakuza, Shinobi might betray all of Krakoa just to save his own skin.
3 Apocalypse
Apocalypse has been one of the ultimate threats to not only the X-Men but to the world over millennia. His inclusion on Krakoa is the most uneasy of the new alliances for readers. His glances at Xavier and Magneto show that something is brewing in the mind of one of the oldest mutants. He has even shown that he has his own agendas that may or may not be for the good of all mutants.
Apocalypse has used Excalibur to involve Otherworld in a way that seems very much like he intends to at least make it a satellite of Krakoa, if not conquer altogether. When the island Arakko showed up to join with Krakoa, Apocalypse revealed his involvement with defending against the threat that exists with it. Apocalypse is up to something, and it may not be beneficial to mutantkind.
2 Sebastian Shaw
In a way, Sebastian Shaw has already betrayed Krakoa. His murder of Kate Pryde, expecting her to be unable to be resurrected, is clearly an attempt to seize control of the Hellfire Trading Company. Now that she's back, what Kate and Emma Frost will do to Shaw remains to be seen.
Shaw really hasn't broken any rules of Krakoa yet. Mutants have killed other mutants numerous times. They can be resurrected and some have priority over others. However, it has been stated that the laws of Krakoa are still being written, and Shaw's actions could be elevated if he sees his power being threatened.
1 Mystique
Mystique may sit on the Quiet Council, but she has made no secret of what she wants. She demands that the Five resurrect her wife, Destiny. Unfortunately, Moira MacTaggart has banned all precogs from Krakoa. When Mystique finds out, she will see it as a betrayal.
Mystique has never done well when she lets her emotions fuel her actions. That could be her downfall. However, when given the chance to plan, she can be one of the most deadly mutants ever. If Mystique decides to take everyone down for betraying her, she may just be able to succeed.