Indies are not the only thing that sony is doing. It's just a market they saw emerge in the last year with digital sales of Mutant Blobs Attack, Escape Plan and others - and naturally are going deeper into it since it was successful. But it's not like they aren't making Killzone anymore. They want a balanced portfolio.
Though I would guess (and really, i'm just guessing, no one told me this) that they see this as a bridge to when the PS4 comes out and the device becomes much more useful to more people.
But take, say, 10 indies, 6 or so new indie/PSN games... and the bigger titles that we know like KZ, Tearaway, Y's, soul sacrifice, Velocity Ultra, NGS2, MLB The show, muramasa, god eater 2... and you have a pretty solid lineup. And we know, being that it's february, that there's more coming than just that.
Sales suck, everything is doomed, none of these games are system sellers... fine, whatever - not arguing that. But as someone who owns the device there sure are a lot of freaking games I need to somehow come up with money for.
