A 2019 MacBook Pro 16" will be perfectly fine for the next 3-4 years. Apple will still have OSes that run on it for at least that long, and most third party software won't even be ARM native until the end of that period, anyway. And besides, do you want the first generation of new-technology Apple?
- The 1994 Power Mac 6100, 7100, and 8100 were built on NuBus architecture, which was switched out for PCI after that generation. They ran 68k apps no faster, and often slower, than their Quadra predecessors. PPC-only MacOS didn't come about until OS 8.5 (or was it 8.6?) in 1997 or so. By that point, even the newest Quadra 840 was already four years old.
- The 2006 MacBook Pro and iMacs, if I recall, could run PPC software (via Rosetta 1) faster than most G4s could run, but not quite as quick as a G5. Of course, this was fine on the portable side, but less good for the iMacs. Intel-only Snow Leopard didn't come around until 2009, and even the last PowerBook release would have been four years old.
What this suggests is that you should expect native software support for four years, and have a computer that's at least as good for most tasks as an ARM machine for half of that, if not more. Given that it sounds like you don't keep your stuff for more than three years or so anyway (2017 MacBook Pro and iPad 10.5" are already traded), you should be perfectly fine with the MacBook Pro 16".
One thing I suspect is that the Mac Pro tower might be the last thing they switch over or discontinue, due to the extensibility of the architecture (RAM, GPUs, PCIe cards), as well as the fact that we haven't yet seen how an Apple ARM chip scales when it comes to handling that many cores. Third party software is also very slow to update (witness Catalina), so I'm betting you're safe with Intel support for a while.