The source code would keep this game alive for another 20 years from now. I think it is possible, but definitely not an easy task. The game itself is still the best candidate for long-time improvements (like OpenTTD).
EA open sourced (at least some) of the C&C games recently. Does someone have idea why or how this one was pulled off? That series was also very popular and long-lasting, although the first game dates to 1995.
I think this needs somehow a coordinated effort starting from mapping the idea of terms and conditions related to the future use of the source code and trying to find the current contacts from EA. Not sure, but one possibility would be to get a permission for prioritised code fixes, and update the most critical parts of the code bit by bit. Someone more experienced community members can probably have an good idea what those fixes could be.
Thanks by the way for all active members here, I have been enjoying SC4 (and Simtropolis too) for long time, not contributing though! Just finalised by profile after 17 years