I don't think people buy indie games because they're about $10 cheaper. If it were, they'd never bother buying an indie game.. there simply isn't enough game for the buck to match an AAA title.
I think people go for indie games because most of them are different and appeal for other reasons (puzzle-lovers, classic game lovers etc.). So I think we shouldn't really worry much. After all, most AAA games end up in the bargain bin anyway.