I didn't watch the crossover so I have no idea what deal he made but if they intend to kill him. They'd give some kind of flashback to that conversation or they'd include another one.
At the same time, they do seem to just expect fans to watch the crossover. Some plots which would be better on each original show has happened during a crossover - weddings, Barry/Cisco conflict resolution - I still have no idea how they made up.
Regardless, I think Oliver is safe.