Long after Commodore died, updates to 68k AmigaOS were released, however I never quite understood why the update phase never went through possibly updated rom chips as well, e.g. Kickstart 3.2 or similar? :-) Wouldn't it be easier like that? We would have a less of a patch-o-rama system nowadays. I suspect that there was a lot of legal bulls**t behind it.

Yep. Cost was the big issue. Escom were the only post-C= owners willing/able to invest in new chip designs/productions, so when they went under, that was the end of new kickstart chips.

Kickstart 3.2 was a 1 meg chip, and I don't know if it could have been salvaged and adapted by later owners to the existing Classic Amigas either.

If it's possible to pull a 3.9 image from RAM, you could build a flash kickstart (see Aminet) and burn the image to that. It would only work in an accelerated 500/600/2000 though.