Apparently there's a date of April 2014 around this. But, as they said: "XNA Game Studio remains a supported toolset for developing games for Xbox 360, Windows and Windows Phone," said the representative. "Many developers have found financial success creating Xbox LIVE Indie Games using XNA. However, there are no plans for future versions of the XNA product." Here the article on IndieGames.com
As these things go, I'm now flogging a dead horse. If the support is not guarenteed, there's absolutely no point in carrying on with this framework. So, I have a rather big decision to make. Port, or abandon.
Seeing as the whole world has seemingly adopted Unity, that does look like the best use-case at the moment. Although there's a lot out there, including Crytek's offering. But all that effort? Starting from scratch now, while I've got two other (non game related) projects already going seems a bit too much.
I can't even begin to hint at a direction in this blog post. It's all a bit depressing, really.