I think this highlight the problem with this approach. $500 MSRP would likely not be cost effective for a phone manufacturer to invest in the design, construction, inventory of replacement parts, and multi-year long support of the rugged and long lasting phone. An important part of the premise of the author is that the phone lasts a long time, and your stated desire for long software support.

This is likely a money loser for a phone manufacturer from day one. My guess is that this phone would likely have to cost $2000 to $3000 for a chance to be economically viable. The biggest expenses are going to be on the human labor parts of a staff to provide the regular software updates, maintaining humans that run the manufacturing lines for the replacement parts, and the repair staff to effect the repairs over time for customers. Considering the only time the phone manufacturer gets money is from the initial sale of the phone, they have to price it high enough to cover many years of these support operations.

At the higher, more realistic, phone sale price it likely drops the number of potential customers so low to not even pay for the initial design and tooling to be created.

This is likely why no manufacturer makes this theoretical phone.