While I'm not a 737 expert, I have evaluated flight software (FSW) and vehicle management systems (VMS) on Gov't programs. Mr. Ewbank points out systemic deficiencies in the 737 VMS and controls.
It would seem the question to be answered by the FAA is whether they intend to address these systemic deficiencies or just the proximate causes of the crashes. It would be a valid, and more rigorous view that since these aircraft are already out of service in an unprecedented way, these systemic issues should be addressed as well. To be clear, it will involve significant engineering work to do so.
There will be immense pressure on the FAA, especially since the aircraft has been out of service and damaged Boeing economically so much already, to just deal with the proximate cause (i.e., stay the course they're on now). That will come from Boeing of course, but also internal management and their perceptions, as well the implicit or explicit pressure from the political class.
Speaking purely for myself, I hope the FAA does force the root causes to be dealt with as Mr. Ewbank advocates (I don't know him, but have immense respect for his coming forward like this - you have to know and understand the systems to be able to provide this kind of critical review).
However, I wouldn't at all be surprised if the fact they have already started down the path they're on causes them to retrench and leave these root causes unaddressed.