First of all, Steven Wright expects to be healthy for spring training and in that case would be next in line to start. If we need to move Eovaldi to closer, it's quite possible that Wright pitches at a high level.
Second, I'm really not sold on Kimbrel's continued success. If the Sox do sign him, they need to go as few years as possible.
Third, I also think it's possible that at some point Chris Sale transitions to closer. He just doesn't seem to have starting pitcher stamina. He looked great in the last inning of the World Series.
Fourth, if Barnes or Brasier does make a successful closer, then we need to give larger setup roles to Johnson, Velazquez, Wright, and Workman. I think it's quite possible they can be effective at middle relief.