I am in the process of changing carrier, I bought my wife her 830 last year half way through a 2 year contract, it's still working fine with Windows 10 on it, and her contract ends this month, so going sim only.
To follow suit my contract ends March so I will be going sim only initially on my 1520, with a view to buying it's replacement when I figure out what that will be with a few possibilities, a 950, 950XL, any high end Windows device released by other companies or of course the rumoured Surface phone.
I have two issues with my 1520, the touch is fine on everything bar web browsers, I can work but not the best experience, and my microphone goes a bit deaf on phone calls, but it's fine on Skype...........
So the end is coming, but not for a few months as my eldest daughter is getting married this May and I need a new suit and stuff.