If Windows phone isn't dead yet, it's certainly coughing up blood.
Personally, I had to buy a refurbished Icon off amazon a couple of months back because my carrier, Verizon, has already decided windows phone is dead and doesn't offer anything better than a refurbished two year old flagship.
My family thinks of me as a phone hobbiest. In order to get a new phone, I had to buy a used phone, then upgrade it to 8.1, then denim, then install the insider app to take updates so i could run windows 10, then deal with a bug in .264 that rendered my phone a hot glowing blob with a half hour battery life until the last update. And I can never get Redstone, so I will be left behind again, this time with nowhere to go. Who would leave another platform for that experience?
Windows phone is Latin. You can still learn Latin, but there's really no one to talk to, so the network effect is really limited.
It's that network effect, or more precisely the lack thereof, that is causing problems for windows phone. Think of a healthy network effect as oxygen. As market share falls, the oxygen gets scarce and it's harder to breathe. Apps suffocate, and key apps die off all together. This lowers market share further, and more apps die off. It's a feedback loop.
I personally came to windows phone because I was sick of being Google's product and Apple was too controlling. Microsoft had the best privacy policy, and windows phone 8.1 was about to launch and promised big things. The only reason I am here today us because I was already here.
Ask yourself, who in their right mind is leaving another platform to come to windows 10 mobile today? Certainly no one on Verizon, because Verizon doesn't even carry a current model, let alone offer a flagship. Anyone under 30 would never, because none of their apps would be available, or if they were would be undependable or lack major functionality. For them Microsoft itself lacks the cool factor, and forget about telling them about using web pages when what they know are apps. It just doesn't happen.
So yeah, dead. All that's left are a dwindling number of people who were already here. That's becoming true even in emerging markets like India where Microsoft is dumping phones.
So dead. Very dead.