In regards to the future of canon ecosystem one has to question this:
In 10 years
Where will the EF-M mount camera/lenses be?
Where will the EF mount camera/lenses be?
Where will the RF mount camera/lenses be?
In 20 years?
Canon hasn't pulled off a major switch on lens mount since the move to electronic killing the FD mount. To me Canon has some tough decisions to make. I think the EF-M is dead yet they released a new lens for it. I don't think it's business smart to carry 3 systems. Something will have to give. RF is without a doubt Canon's future. EF-M will die first. When will EF die? Perhaps another 20 years but you KNOW when Canon does release a top end RF camera they will start to slowly transition to that RF mount as the primary system and the EF will be considered legacy. I think we'll see another 3 cycles on cameras in the EF format (~10-12 years) only to give Canon time to build the RF mount into a full system. Canon doesn't want to be like Sony (think A-mount) and will try to make seemless transition this go round to help support it's customer base longer without making anyone feel it's obsolete. I bet you anything Canon will support the EF-M mount a tad longer BUT cripple it's lineup to MAKE people WANT to upgrade (Thus allowing the customers kill the system off itself). <---this totally sounds like Canon (crippling lineups for preservation of top end/future products)
They seem like they can commit to all three, why not?
Aps-c as low end mirrorless, will remain this way. Works for them. Upgrade path isn't friendly but that's ok, it's about building loyalty. A user with Canon familiarity will likely stay Canon.
EOS R is a tough call. Will they eat themselves? The A7 IV will be 15fps monster in a few years, and A9 30fps.. Nikon is on the cusp of 10 fPS.
If current shooting speeds weren't enough to entice DSLR users, these will. So will the EOS R mkii be competitive? If even halfway, they would have to step on DSLR toes. I'm thinking the 6d is dead right now and end of life.
5D has 2 revisions left. 1Dx may continue indefinitely as a niche product. These bodies will remain for wildlife lenses.
It should be noted that Nikon and Canon only released long lenses for their DSLR mounts.