That's just a theory without any evidence.The planet earth has oil reserves for the next 50 years.
I remember that there was another theory coming from soviet or russian scientists that oil is actually a renewable resource and the oil supply will never end.This is another hypothesis without proof...
Yes, that was called "abiogenic hypothesis" - but even if they are much larger or endless (e.g. natural gas will be enough for hundreds of years more) they are centralized. Fracking is dangerous, and normal deposits are concentrated in the Middle East, Arctic, some parts of US so that creates a lot of tensions around those regions.
Industrial thermonuclear power would also be very centralized. But what about "cold fusion" (hotly debated) and things like that - decentralized things?
Inflation will be lessen[ed], surely.
I guess once we dethrone fossil fuels as a centralized source of energy, the issuers of money will be in more honest competition with each other.
Deflational Bitcoin will be competing in a more freemarket way with inflational fiats.
That will force fiats to become less inflational and generally "better" as money (otherwise they will be driven out by "good" money) - better in all ways: as medium of exchange, as unit of measurement, as store of value (and fiat being awful SoV now, especially with the global rally of devaluation towards USD).