Does the fact that other companies have started imitating Y Combinator bother you? In one sense, I know this will make it harder for you to get people with the best ideas (but I wouldn't worry about that for at least a few years - you're way too far ahead of anyone else). But for the community, having the ability to get a little funding for a larger number of startups could turn out to be a good thing.
Even if you can work with 30 startups in each session, that is still a tiny fraction of all the applications you're getting. There must be projects beyond the ones you will accept that still have a shot at becoming successful. If other people are willing to give funding/advice, couldn't that be a Good Thing?