This is not planned obsolescence it's just bad planning, and bad project definitions from the goverment that allowed this to happen.

Yes to planned obsolescence. But it is in no way a result od digital. Heck the 1st G was analog mobile phones. It is to do with the desire or need to link things together. Yes if you still have a 56k modem (i do somewhere) all it will still work. That may change when all phonelines go IP. But w are a good few years from that. But again it is the links that are removed by society. Not in anyway a element of digital tech. But instead people and well capitalism.

Even if comming IP phone lines failed to support the afsk used in old modems. You and I could very much build our own analogue lines (assuming we owned the land between) and communicate from PC to PC. The tech very much still works just like the analog stuff.

These smart meters will still work as energy meters and thermostats, it's just the connectivity and 'smart' bits that will go offline.