Unfortunately, even with Blake gone, the damage he has inflicted on this franchise is going to linger for a long time. You just can’t really recover quickly from the multiple disaster trades and all the top picks underachieving
Dean inherited two young future hall of famers in Kopi and Quick, a young power forward in Dustin Brown, really good u-25 players in Cammalleri and Frolov and a player in Demitra he was able to flip for basically two 1st round picks.
The next GM is going to inherited aging, declining veterans with very little trade value and a bunch of mostly disappointing young players. The only similarity is the new GM will probably be able to flip Kempe for a pretty significant haul of picks/prospects.
Best case scenario for a quick turnaround is the new GM completely cleans house and overhauls the scouting and development staff and we hit a couple of homerun picks that are developed correctly. Chicago was a doormat franchise until they drafted Hall of Famers back to back with top 5 picks, it is possible, but realistically it will probably be a 5+ year cleanup from the mess Blake has left this organization.