Ducati Corse will build 3 bikes for the '25 season. So far, I haven't read anything about their commitments for the last season of the regulations.
If they are comfortable reallocating resources ahead of next season, my money would be on them continuing that trend and no contemplating a return to four factory bikes before '27.
I does seem that they would allow one factory spec bike for their prefered partner. That would mean that said rider would have to spend time testing parts during race weekends, before the reds.