This sounds like a classic case of premature optimisation. Cross that bridge when you get there. Thousands of other deaf parents have done so. Their kids were fine.
Even if they come out hearing, we’d need to make sure they’re raised right — who will teach them how to talk?
Let me respectfully suggest that this is just untrue, a persistent myth about language learning. Hearing kids learn spoken language just fine, even if their parents don't use it. (Parents have a natural tendency to overemphasise the percentage of the time that their kids spend listening only to them. ;) But kids listen to everyone.)
One thing that does happen is that hearing kids of deaf parents become fluent in both ASL and a spoken language. Which is not a problem. It is in fact kind of awesome.