Evernote's problem is that their product is frustrating and crappy. It solves a major problem, so people use it despite the frustrations, but they don't love it, and later they abandon it.

Since they have spent billions of dollars trying to build it already, I will go out on a limb and say that they will never improve, and that they will slowly (quickly) burn money until they either IPO (and then continue on this trajectory but with more money to waste) or run low on cash and fire-sale to Google, who will just move their users over to Google docs after a year or two. Evernote is just going to burn cash at some rate until they run out, the only question is how much cash they will be handed.