We still don't know whether it will be a prequel, a sequel or a parallel story anyway.
I do know that I wouldn't buy into any IT sh!t. Harsh, but IT really is rediculously stupid in the first place.
Even a sequel may be done without any retconning, and with a more meaningful save import than anything we've ever seen before. It just needs an entirely different approach. I'd suggest something with a strong Asari/Salarian orientation. Let the more scientific inclined and advanced species open up the mess to sort it out.
I just hope the protagonist will be something entirely different. Instead of a military type, I hope for a scientist or a private investigator or something. Maybe one who served time several years before, to give some background about excessive use of weaponry, but still, someone who is outside the military hierarchy, with little to no useful connections there either.