Mr Daniel was asked if the next M would have in-body stabilisation. He said that IBIS is desirable and would work well with M lenses as we have already seen with the SL2. The problem, however, is that IBIS would make the camera bigger, in particular thicker.
He said that we would be returning to the dimensions of the M9 and that would be a step backwards after all the efforts that had been made to make the M10 thinner. He did say, however, that if it became feasible to introduce IBIS without increasing size it is something that could be done quickly.
this was back in 2020, but now we have an EVF M body.. so maybe an IBIS is not completely off the table.
I wonder of the lens to focal plane could a limiting factor for fitting IBIS into an M.