I could see Delta doing it. 763ER should be able to do it since Condor used the type on SAN-FRA, but an A330 would be nicer. The reason I could see Delta doing it instead of KL is that it avoids KL having to open a SAN station, while DL is already here and also has a major presence in AMS. But it may also come down to aircraft availability within the JV; if KL 789 (or A330) is the right aircraft and they have availability to use it then they could come. KL did go to SLC after all adding a second frequency on top of DL's existing SLC-AMS service.
Hey D, I too often think about DL and int'l service from SAN -- as has been discussed many times on this thread -- seeing no particular reason they couldn't do here what they are doing in PDX. DL is currently the only carrier flying between PDX and Asia (TYO) and they also serve Europe (both AMS and recently, LHR) from Oregon.
I don't see DL flying SAN-London of course but why not AMS? And perhaps, at some point, even an Asian destination such as ICN (unless KE, their Asian JV partner, would be a better fit.) Personally, I've always loved that we continue to slowly but steadily pick up major foreign flags here -- it makes for nicer spotting and great variety -- but DL certainly has a major presence in SAN already and it would be wonderful to see some of their big birds landing at Lindbergh regularly! And, as already mentioned, they could start int'l flying our of SDIA tomorrow if they wanted.
In another parallel here to the situation in the PNW, DL has major hubs -- SEA & LAX -- located just 100-150 miles north of smaller DL stations -- PDX & SAN -- that have their own int'l traffic needs. It seems to be working up there, so I don't see why it wouldn't here.
Bottom line: I'd be very happy to have another European flag start serving SAN, or DL. And the same goes for Asia. I'd be happier to see Asia as the priority since LH is still settling in and I don't want to see their business/growth here get undermined too quickly by additional competition to Europe. JL has had a nice long period of uncontested nonstop service to Asia -- since 2012! -- and I think it's time for some competition from the likes of PR, KE/DL, HU...