i doubt Windows Phone is dead, as such, but it is a bit of a lame duck.
Microsoft won't let their presence in the mobile arena go, it would be too embarrassing. I think that would be why they are trying to use the same system on all devices. (That and misinterpreting the tablet market as a desire for slate shaped computing, rather than for windows free computing).
If they actually come up with a system that scales between phones, tablets and PCs then it will be easy for them to keep available, even if it is a flop. (They will have niches.)
What I could see is it going x86 family only, if they fail to bulldoze it though to a respectable market share. (They have lots of form for this, leaving the old system users high and dry.)
I don't see why many people would want the current range, I certainly wouldn't. (Apart from the one with the good camera, but I'd still prefer an N808.) The big problem is being locked to an App store when you have a device with poor market share. The BlackBerry doesn't have this issue (and in addition can run lots of android apps, even Firefox.)
This leaves their market to those with a special requirement that the system caters for (niches) and people who would be just as happy with a dumb phone or a feature phone. (And probably happier with the battery life).
I suspect a fair part of their market has been those who saw the name Nokia on the front and thought that's what they were getting, until they drop it and it smashes, rather than cracking the tile it lands on).