[Eomer of the Rohirrim]

I think there's a good chance that Denethor would submit to Aragorn, after all he wouldn't have much support if he stood against Aragorn, and would possibly have become a figure of ridicule or scorn. It would then be probable that Denethor wouldn't want to hang about Minas Tirith for much longer and might even go wandering for the rest of his days, in some sadness.