Well, I would think Tour de Corse would simply be stupid to go back to WRC, as they would lose their new found freedom and event identity in IRC. San Remo similar. San Remo could do more with their layout, go into Toscany again, but again, since the formation of the IRC San Remo has found a welcome home there when the WRC didn't want them any more, I just could not picture the San Remo organisers to be so unloyal to leave the IRC. Alsace and Deutschland Rallye combined is not on the cards at the moment, and despite the brilliant idea of more endurance style events I can't see how this could work. Although the events are close to each other, they would need a 300km road section and move the whole base. For IRC this would not be a problem (see Tour de Corse) and events as Dakar and Tour de France enjoy a huge TV interest exactly for this type of flexibility, but the WRC with all their VIP monstrosities are too much stuck in their ways.
I think at the end of the day the big question could be around the FIA's new idea with increasing event charges to 240.000 Euros for still uncertain TV in return and when they all have their own working timing and tracking equipment. I don't think Tour de Corse and San remo are willing to pay this, when they do have a home in IRC, Deutschland and Alsace would struggle too, and Monte Carlo, that fee surely was not part of their ideas for the WRC return.
To be honest, I would laugh my head off if VW, Hundei all make a fuzz of joining the WRC and all the sudden all the good events, Monte, GB, Deutschland, are all gone!