And Microsoft continues it's strategy of attempting to muscle developers. Microsoft is steadily losing market share to the PS3 (I'm a recent convert myself). While I think the access fee for XBL is so trivial as to be a non-event, I find PS3 to be a much better multimedia device, with better exclusives.
Most of console exclusive IP is tapped out. Games like Halo, GOW, and Fable are increasingly falling into the 'been done before' pile, similarly with PS3 exclusives which have concluded a few major exclusive IP's in the past few years. That means the console war will move into new territory, I think mostly revolving around console performance, supplementary utility and nostalgia factors. This is why there is an increasing number of 'classics' on the PSN, and an increased focus on the integration of social networking and streaming media.
The simple answer is this. Microsoft do not have the market power to force developers to a particular release pattern. In the long term this sort of strategy will be damaging to Microsoft customers, ergo Microsoft itself. Not to mention the negative brand impact that this sort of statement makes.
All of this being said, Microsoft is (contrary to popular opinion) not run by idiots. There will be some kind of valid empirical grounding in this sort of positioning decision, there is undoubtedly some kind of surplus to be captured here.