Good move; but still too little, too late...
Why you may be wondering? It's not because I think badly about the whole Windows Phone line; to be honest I kind of like it (still using WP7.5 myself because I like my 8 medium sized tiles on screen (and the small arrow indicator) better than the new "either extra small or extra large tiles" kind of choice (which you get with the 7.8 update; at most you'll get 6.5 medium sized tiles on your screen unless you resort to using extra small tiles)).
Even so; although I think this is a good move it's still a bit too late. They should have been doing this with WP7 instead. Because most interested people & fans bought into that because of 3 main issues:
1) Support: Windows is supported for many years; so most buyers expected the same with Windows Phone.
2) As if #1 wasn't enough; Microsoft explicitly stated that dumping Windows Mobile 6.5 (the predecessor of WP7) was somewhat of a mistake which they wouldn't repeat.
3) If the previous points weren't enough: in addition to #2 Microsoft even started making specific demands to the hardware, convincing many people (yours truly included) that they were carefully aiming for the future.
Well, the results should be well known: WP7 got one (desperately needed) update to 7.5 and that was basically it. After that WP8 got announced and although Microsoft denied it many WP7(.5) users realized that as soon as 8 was out (which isn't downwards compatible; native WP8 applications do not run on WP7.x) it would also mean that support for WP7.x would rapidly decline. And it did.
Although I'm not complaining (I prepared myself too much for that) it basically resulted in me getting a "modern" smartphone, only to learn that it would be obsoleted within a year. NOT the kind of result I expected from a Microsoft product. And judging from several WP fora I don't stand alone in this.
SO yeah, this is a good move, but the previous ones have already cost Microsoft a lot of goodwill. Because the so called early adaptors of their product sort of felt being left in the cold. And I somewhat doubt that those guys would recommend a Windows Phone. Heck; even though I'm actually pretty happy with my WP7.5 (I don't like the 7.8 update) I wouldn't recommend a Windows Phone perse. Because if you get one then there's no telling how soon support will drop.
"No, you're wrong; WP8 is "an even better choice for business"" (quote from a marketing mail I got).
But like; that's what you said about Windows Phone 7 not much longer than a year ago as well, and look where we are now...
And although I'm not much of an Android fan (mainly because of Google, which I consider very intrusive) nor Apple you got to admit that they both provide much better upgrading scenarios. Even if you have an older phone there's nothing stopping you from installing a more modern OS.
Sure; it may not run as quickly as a phone with more modern specs, but the fact remains that if you buy a "top notch" model you may very well end up with a phone which can last for years (and with that I'm referring to years of continued support).
Microsoft had that exact same reputation, but didn't (couldn't?) live up to it. And now when the damage has already been done they're all of a sudden starting to extend support cycles and stuff.
As such my post title: too little, too late.