STARK R&D is something I’m personally incredibly interested in, and one of the reasons I wanted ZIP 1014 amended as described here: ZIP 1014-1: Proposed Amendment to the “MG Slice (Major Grants)” Section - #5 by kayabaNerve
ZK-STARKS, as of right now, doesn’t further Zcash because Zcash doesn’t use them. That said, I believe post-quantum privacy protocols undeniably benefits Zcash (even if it does also fall under the “furthering financial privacy” exception). I also believe there have been post-quantum SNARKS formed, yet I can’t claim to know nearly enough on how comprehensive they are (would they work for parameters akin to Sapling? How much worse would the performance be?).
As for knowing addresses being enough to break Zcash, I believe that should be assumed. While there is theoretical value in knowing the distinction, any nation state who has access to a quantum computer can easily access either historical traffic, public posts, or exchange records. The only possible advantage is the plausible deniability created if you immediately move the funds to an address only known to your local computer to break the trail (churning). That said, with HDKD, wouldn’t you need an entirely new seed for this to be successful? I don’t know enough about Zcash’s current HDKD scheme to comment, nor on quantum computing application to HDKD schemes.
If a donation pool was established to work on this, I would very much want to donate. I’d also love to see grant work on the topic proposed, though I’m not a member of ZOMG and may never be so that’s a moot point for right now 