Seems to me that Boeing were originally hoping for the cheapest, simplest fix being:
Software modification AND acceptance that existing training regimes are (should be) adequate - hence the repeated statements that "properly trained and skilled crews" should have been able to recover the accident aircraft
But every passing week has made this less accessible as a solution as it has become apparent that MCAS operation does not resemble any "normal" trim runaway training and that stalled trim procedures have been consigned to the dustbin of history(Probably rightly).
So the Boeing desired outcome now becomes accepted software mod WITH additional training (for which, one imagines, Boeing may wish to make a contribution)
OR
if this proves too difficult and/or expensive owing to complications arising from processor lag or who knows what else, then there is the option of an aero solution, though hard to see how this can be effected in any short time frame on existing airframes
BUT BUT BUT
The manual trim wheel thing strikes me as a showstopper in either case above
If the wheel is required as a risk control then it MUST be usable in the case where the risk has crystallised and the control is required. At present it appears that pilots should use electric trim to control pitch and only use manual trim if that fails. But if this has failed then, by definition, the aircraft will be significantly out of trim and.....
And then, well, if that has to be redesigned, engineered, and potentially cockpit layout changed how is this implemented across the NG fleet??
Nasty questions for everyone methinks