I have to disagree with this; windows phone wasn't a failure. It's a lovely platform specially with a good phone like the Lumia 950XL. It is even better than iPhone and Android OS. We just need to decide whether to migrate to another OS with ROM or to use a modulator enabling us to open all third party applications which were blocked such as whatsapp and others. MS must feel obliged to make this happen for their customers
Make your decision based on the fact that Microsoft will do absolutely nothing. As far as MS is concerned Windows Mobile is dead and buried.