I use my N900 as a daily driver and will continue to do so until one of 3 things happens:
1.It fails and cant be fixed/repaired
2.Something happens in the network that prevents it from being used (carrier stops supporting the needed frequencies)
or 3.I am able to replace it with something better (no way I would downgrade from an N900 to a Galaxy S7 or an iPhone 7 though)