I would guess based on previous discussions about this that the big change, other than QB, will be in the offensive line requirements: pass blocking interior line vs. run blocking, size, longer arms, etc. But I think the new guy will have some players to work with and -- again with the QB -- could have a relatively pleasant first year W-L, including a bowl trip. now, it might be Detroit again, but a bowl game. To me it is reasonable to expect six-eight wins unless the cupboard is completely bare, and I don't think Johnson did that.
And I still expect to see Johnson coaching again with maybe a year off.