It's kind of mind boggling to me that they have a tight chassis, AND it meets their buildable/ugpradeable/repairable goals, AND their backwards compatibility is reaching back five years now.
I think a number of people would have expected these to eventually require a trade-off. Especially coming from pc-building land, where we see new non-backwards-compatible CPU and RAM sockets every 6 or so years.
There's a version of this where Frame.work said, "Design tradeoffs mean the 13 Pro is a new platform that is largely not backwards compatible, but don't worry, the 13 series will still get 5+ years of support and parts" and everyone goes "Aw, well, I guess that's reasonable."
I really want to emphasize that it's looking like Framework is creating a laptop with _better_ backwards compatibility and build-ability than a desktop PC.
All this is to say that this is very very impressive!
Even more impressive than going back 5 years is going back all the way to the first version. While I'm a software engineer, I've worked in teams where we shipped hardware, and for a consumer product with lots of constraints including implicit expectations, going against the entire trend of the past 15 years and targeting a hard-to satisfy market segment, they far exceeded what I expected when they announced their first product.
Its backwards compatible to the first version??? How did they do this.
At some point they will still likely have to force that cut-off, but yeah, it's great that they seem to be able to stretch it for longer than most people would have expected.