It appears that SFO is the
no. 3 interline destination from DUB - I'd say EI feels there is sufficient traffic on the route to merit investigating it once again; I imagine the yield guys in route planning have a special folder for SFO. When the required yield is achievable we'll certainly see a green light - and the yanks are returning in droves to Ireland now, so I don't think it will be long before we start hearing credible whispers.
You'll note that 4 destinations on the list are also served non-stop by EI ops.
And Toronto is another favourite rumour for EI.
Giving a cut - especially a disproportionately large cut to a short haul interline partner - is no airline's first choice.
The other destinations are just too far for EI with their equipment and the middle-eastern giants have been hoovering up that business. (As an aside, I reckon the JNB is actually a mask for much ultimately CPT-bound traffic, as not so many airlines serve it year-round directly).