They've pissed off some, certainly. We know that from those tweets. Microsoft was using the logic that Kinect was bundled from Day One as a way to convince developers that making Kinect games or adding Kinect functionality isn't a waste of time. Really, though, how many developers were actually working with Kinect? A few will be angry but most will probably be secretly pleased that they don't have to add Kinect support to their non-Kinect games--though I imagine Microsoft will still push hard for that functionality so they can do the "better with Kinect" thing.
Long term, though, it won't matter much. This isn't like Nintendo, where publishers and developers don't see much profit. There is too much money to be had from working with Microsoft for most developers to stay angry and most publishers would knock over their own families for a share of Microsoft's money.
However, this could lead to the cancellation of planned Kinect projects.
