Would Suharto have set up one of his sons as his successor
Most likely candidate from Soeharto’s family is his eldest daughter Tutut who by 1998 is in cabinet as Minister of Social Affairs.
Actually, in a political crisis involving Soeharto’s incapacity there is a possible situation where she could be in line to succeed.
In that resolution regarding incapacity, it says that if it’s the Vice President who is incapacitated (read:if Soeharto or his supporters mobilizes enough support from around his bed to remove VP Habibie) there are some options available to him:
1) He can declare himself temporarily incapacitated and, because the vice presidency is vacant, would be required to name a minister as acting president . At this point either Tutut or Minister of Defense and Security/Commander ABRI Wiranto would be prime candidates.
2) He can ask the MPR to go into session to elect a new Vice President.
But there are variables involved. With option 1, Soeharto might get support for the removal of Habibie but the sustainability of the support would depend on who he wants to name as acting president.
With option 2, given that Soeharto would be bedridden, there’s a chance that things are taken out of Soeharto’s hands and certain members of the political elite would try to maneuver themselves into the vice presidency and be in a position to succeed Soeharto.
At the very least, whoever’s the new VP has a good chance to be at least named Acting President because it would be difficult and extremely stretch credibility if an argument is made that Soeharto is not at the very least temporarily incapacitated (In OTL the stroke causes him to lose clear speech and made him very emotionally unstable).