The M going digital was logical, even in trying to maintain most of it's form and functions.
Leica's up until the upper 1970's were or still had the 'Leica design tradition'. They were mechanically sound and, complicated to a fault as to the expense of manufacture. But, in the case of a body that today could have been, and still could be a great DSLR body design, then look no further than the masterful design of the SL2.
It's form factor is still second to none, It's body size (w/o the MOT motor drive) would easily encapsulate today's modern electronics - including AF - and either the use of EVF or, my preference, a traditional prism - because an EVF uses more power at least with today's tech.
The near perfect, clustered control, and meter were a joy to use, and even if a built-on grip were desired and the controls it could hold, it would be easily incorporated. Too, the rear display would fit easily as would the mode buttons.
When I think about this, I really do believe Leica completely missed the boat with it's decision to abandon the R line and the large user base even when considering the reasons - 'it would be like swimming with the sharks of Canon and Nikon'; tell that to Sony!
The S line is a fine camera - but sell more than an SL2-like designed DSLR? I still absolutely doubt it.
The consideration seemed to have been lost to Leica at the time that in the SL2 they had a traditional, near flawless Leica design that matched the M in it's lineage and a design that still to this day speaks 'Leica'.
Hopefully, whatever the 'rumored' new M may be, I hope it captures the classic useful Leica design language of the M and - the SL2 - my favorite Leica of all. It's simply a great design.