Harpoons are probably still very useful with subs. I don't know how many encapsulations we have, but the biggest issue with Harpoon, being range, is less of an issue with a sub. Also the lack of advanced stealth features, are less of an issue when attacking less well defended land targets, for ships torpedoes are still pretty stealthy.
Superhornets, P8 and subs mean that that is decent number of platforms. I don't think we will be upgrading them, but I also think we aren't yet ready to get rid of them. If NSM becomes sub launched, and LRASM JSM becoming P8, and Superhornets are getting decommissioned, then it would be useful to get rid of them.
Not sure how useful they would be for Ukraine either. there would be other allies in the region that may appreciate bolting a launcher or reloads if required.