I kinda wish MS just released an open source version of it so development could continue instead of ending the project completely.
Time and time again I saw independent developers making fantastic third-party app replacements for the most popular Android/iPhone apps, like Snapchat. Time and time again I saw them deleted from the Windows Store via a takedown by multimillion/billion dollar companies that didn't want to make a WP app.
I'm sure money was a consideration, but malice was a much bigger factor, and I wouldn't be surprised if Google money played a role in it. A lot of people did not want to see a third mobile OS platform and did what they could to ensure it failed.
It might have survived one of these issues, but both was crippling. Poor app support and constant churn of APIs can't end well.
I still own Nokia 1320 which - if I'm not mistaken, was one of first "phablet" sized devices and I was quite fond of it up until applications have stopped working. Now it just works as any pre-smartphone device: I only pick up calls, send text messages; battery had to be replaced on 4th year which just confirmed the durability of electronics today and planned obsolescence. Back then I've managed to run some beta of Windows 10 Mobile but in the end, my Nokia didn't get it.