Good question. It is very likely that an earlier defeat or surrender would have spared the temple. According to the sources, Titus even hoped to do that OTL, though it's unlikely there was much of a chance of it if Jerusalem was taken by assault. I would assume he'd include that in any formal surrender, though.
The problem is that the Romans would still have to deal with a restive and dangerous Jewish population in Judaea, and likely quite unhappy neighbours, too. The rebels had not exactly been nice to the pagans, the Hellenisers, or even each other. And of course a high priest of Roman making would find it even harder to enforce his legitimacy than one of Herod's creation. Something is going to give, sooner or later. But if it does later - all of Rabbinic Judaism and Christianity as we know it could be butterflied away.