What can Norwegian, or Vueling, really bring to MAN but duplication of what already exists ? There is little public knowledge of either versus the well established MON, TCX, TOM, EXS, RYR and EZY.
The Vueling base has been spoken about for the last year or so, as OW's way back into MAN's shorthaul network (with others making a move on longhaul as OW are not keen on the possible future of VS/DL at MAN), but even with Vuelings low cost base versus BA I still doubt it'll work.
Not often I am doom and gloom, but I just can't see room for all of the above.