I'm not sure in reading this whether you're confusing an M50-II with an M5-II. The rumor mentions the 50, but not the 5.I think the introduction of the M7 and M5 II will mark a clear division between the two two strands (body form factors) of the M range. The M200 and M6 to represent the compact end.
The other part will have built in EVF (which also makes a design statement). Then in order to fit two card slots, IBIS etc. the M7 and I guess the M5 II will end up putting on a bit of size and a hint of weight. I guess the bodies might be a bit taller, to accommodate the tech and our extra fingers. That would also help balance larger legacy glass via the adaptor. Think a slimmed mirrorless version of the 250D. Or something just a bit smaller than the RP. It would also add space for an additional wheel or two.
If they manage to put some weather sealing in the M7 and some subset of animal eye focus they will have a winner. I'll be there for pre-order.
(I love my RP. However my rucksack with the body, 100-400, extender, adaptor and FR 24-105 alone is a lump before I add a 50mm, batteries, filters and all the other stuff.
My M50 and 4 lenses weighs a fraction of my other kit and fits nicely in a shoulder bag).