I was using a 200D but started getting interested in Birds in Flight. Earlier this year I bought a second hand 7DII from eBay. I briefly considered an M5 or M50 before getting the 2nd hand 7DII but they just didn't have the right level of specs, build quality and so on. While the 7DII is "only" 20MP, I'm getting some very nice shots: landscapes using the EF-S 24mm prime, and Birds In Flight with the EF-S 55-250 IS STM.
I don't have a big budget. Pretty much all of my gear is second hand. There's no way (apart from selling a kidney on the black market or divorce) that I'm going to be able to afford a FF mirrorless like the R6 or R5, especially when you factor in the cost of new RF lenses (adapting my existing EF-S lenses is pointless). Sorry Canon, but at that price point in AUD, it's just not going to happen.
However ... if this new "high end" M camera has even some of the specs that folks here are suggesting like weather sealing, 32MP sensor, 14fps+, and so on, then I'd be *very* tempted to sell most of my current kit and invest in the M line. I know that's still a significant investment, but if I can pick up just the body and EF/EF-S adapter, then I can continue to use my EF-S lenses, and swap over to native EF-M over time.
Two card slots seems to be one of the things people are wanting in a "high end" M. Personally, I don't see Canon doing that. It's not really part of the M series design and with the Canon online imaging service thingy (can't recall the name, and I know they're still ironing out the issues with it not working recently), I'd be surprised if they offer two physical card slots, and have only one, plus the ability to backup via Bluetooth or WiFi to a mobile device. I know that chews batteries, and I'd *really* hope they use a better battery than the LP-E17 from the 200D/250D/M50, and go with the LP-E6 series. Also many of us already have a bunch of those, so that's an advantage.
Anyway, for this current DSLR shooter who is very aware that DSLRs are dying and mirrorless is the way of the future, bring on the CR2s, so I can start planning and saving for my next camera!