I think the roster is closer than you think. The problem is the areas it’s still lacking are pretty horsefeathers important (HC, OC, QB, OL). But the defense has basically been rebuilt and despite the terrible showing today has looked pretty damn good at times this year and is full of young talent. Even the OL appears to have 2 or 3 of the 5 spots set with young talent.
I think if you put a legit good QB and OC on this team and build some depth through another draft/FA period they can be good really soon, but obviously much easier said than done.