I think it is actually IAG that has the LGW slots, so my guess is that a combination of Vueling, Iberia, Aer Lingus, Level and BA will utilise these slots to places like ORY, BCN, MAD, FCO, DUB etc in order to keep them "active" until the time comes when they can properly reallocate their fleet and come up with a route strategy.
Or, whereever Norwegian currently fly to from LGW!