Honestly, canceling lower-sales-tier books is something Vertigo has been doing since, well, soon after they began, really. If you recall, the launch of Vertigo actually happened with the first issue of Doom Patrol AFTER Grant Morrison's run, so Rachel Pollack "only" had 23 issues on the book before it was canceled. Animal Man lasted 32 issues. Swamp Thing lasted 41. So even most of the ORIGINAL books in the Vertigo line were canceled within a few years.
So what we're seeing today is nothing NEW, but boy, is it sad to see such impressively diverse books like Unknown Soldier, Greek Street, Air and Madame Xanadu (has Madame Xanadu been officially canceled yet?) end and it makes me extremely grateful for every issue I get to read of the great non-Fables books Vertigo has to offer (as Fables is not going anywhere any time soon, so I don't have to worry about it).