So, the fusion we are talking about here is deuterium - tritium fusion as it should be the easiest to achieve. Deuterium is not a problem. A rough estimate says that there's enough of the stuff to cover 100% of the world needs for thousands of years. And it's easy to breed: surround the reactor with water so the hydrogen there can capture the stray neutrons.
Tritium, on the other hand, is a problem. It is radioactive with a half life of ~12 years and so the little we have needs to be produced since we can't really accumulate it. Currently it is produced by conventional nuclear reactors. Additionally, breeding tritium is harder than deuterium and requires a blanket around the reactor that uses other materials to multiply the number of stray neutrons. For each atom of Tritium that is fused we could get somewhere between 1.1 to 1.7 with a theoretical maximum of 2 Tritium atoms so, finally answering your question, it is renewable. It's just hard, but a piece of cake compared to actually maintaining a stable fusion.
I don't see it as intractable. We already have two ways to do that at scale. One is proven (the fission reactors), the other one is proven but not in an actual fusion reactor yet. Iter will have such a blanket for tritium breeding.
Intractable in my mind sounds more like something that you don't know how to even start.
Tritium, on the other hand, is a problem. It is radioactive with a half life of ~12 years and so the little we have needs to be produced since we can't really accumulate it. Currently it is produced by conventional nuclear reactors. Additionally, breeding tritium is harder than deuterium and requires a blanket around the reactor that uses other materials to multiply the number of stray neutrons. For each atom of Tritium that is fused we could get somewhere between 1.1 to 1.7 with a theoretical maximum of 2 Tritium atoms so, finally answering your question, it is renewable. It's just hard, but a piece of cake compared to actually maintaining a stable fusion.