I don't think so. I think if they go to Jordan Love at QB they will do everything they can to surround him with enough talent to be competitive. I think a young QB benefits from a solid OL, good run game and strong defense. Replacing a QB is not rebuilding.
If they really were rebuilding it might be smartest to rip the bandaid off...that would look closer to tanking this year though. Don't see that happening.
Doubt they bring back Preston if they are rebuilding.