That was me. I suggested either Davies or Kwan's ridings, which are very solidly NDP and the sort of area that Singh is meant to appeal to.Sometimes he says he wants in as soon as possible, other times he says he'll wait until 2019. His challenge is that there aren't a tonne of safe NDP incumbents. In the old place, someone suggested Don Davies' riding in BC, and that seems like one of the few good fits, but Davies is pretty active, and it doesn't seem like he'd be up for stepping aside any time soon.
Singh could announce his intent to run elsewhere in the 2019 election and just be using the Vancouver seat as a placeholder, at which point the old MP could reclaim it; there's a long tradition of that happening, e.g. Scott Brison temporary vacating Kings-Hants so that Joe Clark could run there; Fernand Robichaud taking a hiatus from Beausejour to make room for Jean Chretien; Elmer Mackay letting Mulroney have his seat for about a year.