I'm thinking they'd be trying to convert him into being their 6 since Nico hasn't gotten time there.
#9/Aubameyang or Depay/Gavi
Ferran/Adama/Winger/Gavi
Pedri/DeJong/Gavi/Nico
Kessie/Busquets
Would be my guess. No first XI spot for Gavi, but he can be used in various front positions as an alternative (tucked in winger or false 9) off the bench, and he's still only 17 so probably like 20 starts and 30 sub apperances is enough for now to not ruin him.
A new winger or Dembele stays. Then add Christensen or another CB and probably a new fullback on each side.
Xavi wants to have 6 high-level midfielders. The season is long and there will be injuries.
Gavi is performing at a very high level, better than De Jong. Right now he is a starter at Barcelona, without discussion.
I don't know which player Xavi has planned to replace Busquets. The normal thing would be De Jong or Nico.
Lately there is talk of interest in Tchouameni, for my fake news. And Gravenberch, I don't know if he plays 6 or 8. Having the players that the team has right now the money should be for other positions.
Gavi/Kessie - Busquets /De Jong - Pedri/Nico
Some of them can change positions, so there is no problem to fit them.