Stop using proprietary HDDs, controller protocols etc. This is one of the few things Sony got right this generation but I'm afraid MS don't feel enough pressure from them to do the same.
Stop charging for Xbox Live. But with Sony not being competent enough to provide a service that can compete with Xbox Live I doubt they'll have any reason to do so. I wish that Sony would launch ahead of MS (not gonna happen) and apply some pressure.
Provide a decent app store. Apple must be kept out of the gaming space at all costs. I want my developers to focus their efforts on $50 million projects, not on silly Angry Birds derivatives that would have been free Flash games on some obscure website 10 years ago.
But knowing MS, I doubt they will do any of those things.