I came from android quite recently. I used to cook roms, mainly for the note 3 as the manufacturers attempts were errrrr.....P*SS POOR. Samsungs had so much bloatware it was ridiculous. If you wanted your phone to perform well, you had to root / go the custom route. Guess what? Samsung in their infinite wisdom created KNOX. If you decided to run a custom rom, the knox fuse would be 'damaged' and they refused warranty claims. They now have most of their flagship devices locked down.
Although the windows system is very 'securely' locked down, the lack of excessive bloatware makes it very useable, and even a basic model like the 435 can run Asphalt 8 without glitching.
When I took the leap from Android to WP, I found the range / models, VERY confusing. Same model number but single or dual sims, the 635 comes in lte or 3g with either 512mb or 1gig or ram, and so it goes on. Hopefully, with the 'restructure', this confusion will be diminished. I am well aware of this because, I took a 930, the wife took the 640lte, which by the way seems to be a well built device and nicer in the hand than mine (!!!!), my son of 15 now has a 635, again very nice to use, my daughter has a 535, again nice to use and no issues with the screen, and my autistic son has a 435 which is as cheap as chips, should he lose it or bust it. We got all of ours from a UK shop and all of them were unlocked (except mine!!) My 15 year old takes his to school and, despite the stigma attached to WP, his mates are quite impressed, although they will still buy the latest all singing all dancing samsung, because......it's sexy and allows one upmanship, and it is a great 'fashion' item!
I think the biggest issue with WP, is that they just aren't 'sexy', and lose their appeal to the younger prospective purchaser. As mentioned above, WP has a stigma attached and they just aren't viewed in the same light as the shiny new Android / Iphone. Then again, at least my kids won't get mugged for the latest devices!!! It also doesn't help that MS use older chipsets. Why anyone would want an octacore processor in a bloody mobile phone I will never know. I guess MS's retort would be that R&D costs would be negligable by using last years chipset.
I think they will still be around, with a greatly reduced, less complicated line up of devices. I'm guessing that the devices will be manufactured by thirds parties. Sod samsung et all, how about 1+One and HTC?