I'm sure a Galaxian3 reboot wouldn't not be difficult to do for Namco.
The pre rendered background originally used is really basic comparing to what any home console can do in real time nowadays.
It's almost the same work than they've done for Starblade, except yes, to think about the background solution to use (reuse the original video footage, or render it in real time)
It would makes sense to do it, this game in a part of UGSF series after all (Galaxian, Galaga, Starblade...)... and in addition, they may release the Zolgear mission, which is NOT available for any other system expect of course the arcade version.
If I win the lottery, I would commission Namco to do the job, or even better... make the game on a reliable PC system, to be interfaced with the real GT6! Let's dream
Who want to Kickstart this?