I do believe I've seen plans/read something that had a Galleries Club in T5C, like in B. Maybe the thought is not to fit it out from day one but to at least leave the space for one to be fitted - the GC in B didn't open from day one while flights transferred from T4 in stages - perhaps T5C's piers will be gradually opened and the GC there will come later but not far behind? It would seem though that with 380s departing from C, it would make sense to have a lounge instead to supplement the capacity in A.