It's an interesting question to pose which problems reduce to factoring (or discrete log), and whether any of those problems could be of practical value. In general I think the consensus is that most such problems are of some number-theoretical bent in the first place.
There's a 1987 paper from Heather Wolf that proves and lists some reductions known at that time:
Whether any other reductions are known, since, say, Shor '94, that are of industrial relevance, I am not sure. I've often thought about reducing factoring to finding Golomb rulers but I don't know enough number theory to make headway.
Factoring (and discrete log and related questions) are such unique problems in computer science - Aaronson often quips that if we can factor numbers easily then we can collapse the entire world economy but we wouldn't collapse the polynomial hierarchy.
Graph Isomorphism is another problem of much practical importance, but alas this is not known to be in BQP (and our classical algorithms are pretty good anyways).
I do disagree, though, that "the algorithm becomes obsolete once all data is encrypted using post quantum cryptography". The website that I'm writing this on, right now, says https - all of those private keys are ripe for the taking even after conversion to post-quantum cryptography.