Most free games suck massive balls. Dungeon Keepr is not the first, just recall Ultima Forever which recently announced bankruptcy.
I think that many gamers will still favour quality... mate, it's not that you crack a game every few days, a good game keeps you hooked for at least a few weeks in solo mode and maybe years if it's an online one. Freeemium will either be so easy that it sucks or impossible without purchases and thus not attractive in any of both modes.
but we may be wrong; giving price liberty may be a good move, because it doesn't necessarily mean that developers will do freemium.
Also recall that the best and most valued games on the mobiles plaforms such as Infinity Blade aren't free !