Until you're able to somehow transplant a T420 keyboard into a Framework, I'm staying on my ThinkPad either until it dies, or the heat death of the universe. whichever comes first ;-)
Are you listening, Nirav?
(Yes, I know it would make the laptop slightly thicker and heavier. But I just said I'm using a W520, and happy with it...)
Still, it's not a complete nonstarter for me, because the 16 does have that optional keypad. I could actually start using the numlock key again.
All those off-center keys have been grouped, offset and/or specially shaped since ages for a reason - to immediately and unambiguously settle your fingers there with minimal error when you have to move you hand away from the homerow anyway.