Let's say that we start with a dedicated Champion Edition Capcom Big Blue cabinet.
Would it be possible to do the following modifications:
Have the built in controls usable, but have the option of plugging in modern console sticks and control pads. Both 1P/2P have the ability to choose between the built in controls or plugging in a stick/controller.
Fit a computer to use Fightcade (or similar online multiplayer platforms) into a cabinet that also has a standard CPS1 or CPS2 setup, and be able to switch relatively quickly between the two. Again with the ability to use either built in controls or external plug in controls.
Add RGB video out & audio out for the PCB for streaming. I'm not sure if you can just split the signal going to the actual CRT & cabinet speakers, or you would need to add some sort of other interface board in between.
Since a computer for Fightcade could potentially be tiny non-powerful machine, I'm sure it would fit. I just don't know what solutions would exist for easily switching between a PC setup and the actual PCB.
BTW, the question isn't specific to CPS1. It was just an example. I would potentially like to do this with an MVS setup or a CPS2/CPS3/Naomi cabinet.