If Apple takes on the gaming market and develops a few of their own in-house games, you can bet your bottom dollar that they will be pushed front and center and other games shoved to the back.
I am the biggest anti-Apple fanboi in existence, but I don't see the connection here. All of Apple's marketing for the iPhone and iTouch is about third-party apps. There is a huge Apple billboard outside my office advertising a bunch of third-party games for the iTouch. So if they start banning third-party games, this will be an unprecedented reversal in their current policy.
As an aside, I am looking forward to the day when I can get AdBlock in real life.