I do wonder what percentage of EF-M users would even consider a full-frame camera. Let's say an M200 styled camera in RF mount would cost $550 with a lens. Is that enough of a difference for the person to not consider the RP at $1300 with a FF lens? Would people that have any interest in FF consider an APS-C starter when their kit lens and camera don't get them there? Sure they could buy this M200 with an RF 35mm f1.8, but that combo is getting close to the RP plus kit lens price. I can't see many beginners starting with a 35mm prime even though they might benefit from it. Back in the DSLR days, there was more of a reason to start in APS-C. Not until the Nikon D600 did FF really start to drop in price (I switched from Pentax to the D600 so I could try FF).
I could see Canon trying to follow Nikon for better or worse. I tried the Z50 and it is a decent camera, but it has a lot of drawbacks and will for a long time based on their lens roadmap. The current Z-mount FF lenses aren't amazing focal length combinations for a crop camera. It's totally possible Canon is willing to drop EF-M out of stubbornness.
What benefit is there to APS-C cameras in a FF mount? I guess maybe a sports focused camera if Canon had a fast and recent lower resolution APS-C sensor to source. Besides that, Canon already has RF pretty covered from $999 full-frame to high resolution with the R5. I wouldn't expect them to handle it any better than EF-S. I'm seeing 19 EF-S lenses on B&H right now with 4 of them have an aperture f/2.8 or faster.
Full-frame is a lot more accessible now than it was. I see the benefit of APS-C in the potential size of the lenses and to a lesser degree the size of the cameras (the RP is pretty small, so much so I prefer it with the grip extension). Okay, I guess people really want an 80D or 7D in RF, buy why? What would those as RF, updated to current tech, really get you over what current RF FF cameras that exist?
Fujifilm shows what dedicated APS-C can look like and it makes the most sense to me as the path of that sensor size, though maybe Fujifilm's APS-C will die out eventually... who knows. How much pricing room does Canon have in RF for APS-C? We'd probably see a bigger M200 styled camera. Maybe the sports camera if a sensor exists. What else? An M6 II with RF mount? The rest of it seems covered by current FF cameras. Right now the only recent APS-C sensor we know of is the 32mp one.