Assumptions all over, but... imho re-entry into service could be achieved by the following:
- ensure MCAS can only activate if both sensors agree;
- ensure the original cutout which pilots relied on for many years (column cutout) is instated for MCAS cutout
The above can be fixed by software for condition 1. and some change in circuits around the column cutout for condition 2
How these changes are made is likely to remain confidential until approved to ensure the impartiality and integrity of design changes.
Time will tell, think it won't be much longer as the earliest time it takes for these stages to complete is coming towards fruition soon.