Who knows is exactly the problem. Hand waving this away for future generations to deal with is exactly the problem. If we can’t imagine how we’ll solve it, we should probably strive not to create the mess.
(*) I'm more or less convinced that such a miracle technology is the only hope we have of avoiding catastrophic change. I'm baffled why there's not massively more funding into researching potential geoengineering solutions, given the stakes. Even fossil fuel companies would benefit!
What we do use helium for today are things like MRI machines that are medically invaluable, and we do so wastefully potentially denying future generations this technology.
Even if we eventually find alternatives, it may be inferior or we may otherwise deny them technological advantages of similar importance that would be more accessible through access to helium.
The problem is that today Helium is cheap enough we’re happy to boil an MRI machine’s worth off into space for a child’s birthday party.
Climate change is simply another face of the same coin of indifference to the costs we confer on others.
Apparently there's plenty on the moon...