LurkerJ on 17 May 2015
You are forgetting about manufacturers too. MS has eliminated both obstacles. I don't live in the US and my flagship premium device, the Samsung galaxy S3, was supported for a less than a year! Nothing to do with my carrier..
Developers will love the news, app makers will find it a lot easier to make apps for windows phones. The news in the OP and the fact the adoption rate for windows 10 will be phenomenal are the main reasons windows phone will get supported (I don't buy the hype behind the porting tools MS was talking about days ago..)
