This looks to me like typical Microsoft strategy that they utilized a lot 25 years ago.
1. when not leader in given market, make your product fully compatible with competitor
2. start gaining momentum (e.g. why should I use Linux, when on Windows I can run both Linux and Windows applications)
3. once becoming leader break up compatibility
4. rinse and repeat
Happened with MS-DOS, Word, Excel, Internet Explorer, and others.
And as you said, there is nothing new in this. The whole "hell freezes over" thing gets a bit old because Microsoft has done this same routine countless times before. When they are the underdog, seeing a fleeing userbase, etc, they pragmatically veer towards open and integrated. When they aren't, they close off and exploit. (see Microsoft's arrogance and hubris as they exalted in their success with the Xbox 360 -- early initiatives like XNA, their unloved community gaming thing...abandoned and left to die -- and now that they're losing with the Xbox One, once again that wonderfully open and accommodating company returns again. People pretend it's new.
Another example I would give is MSN Messenger -- Microsoft did a loud, public campaign, including taking out ads in newspapers, pushing an open messaging platform, interoperations, etc. Microsoft had just started to get into the messenger game, so of course they didn't want to be kept out via the network effect.
Then, of course, MSN gained users (being pushed on users, automatically configured, tends to do that). Microsoft made a complete 180 in approach. Soon they incorporated an expensive licensing program that third party apps had to use to interoperate with MSN Messenger, endlessly doing technical fixes to block third party access.
What happened to that gregarious, open and cooperative Microsoft that was taking out ads to implore AOL for blocking access? The situation changed, and suddenly it wasn't in their interest anymore.