Don't see it happening unless Jim remains in Labour. Basically, any chance he had to be PM disappeared when he quit over Rogernomics.
Similarly, Winston Peters blew any shot he had when he left National.
Deputy PM in coalition is the closest either will ever get, as neither man is capable of marshaling enough voters to win either a majority or even a plurality. Even then, for Anderton, he needed the support of the Greens and the remnants of Bruce Beetham's Social Credit to get anywhere near enough electoral power to be considered as serious coalition partner. Once the the Greens left the Alliance, he pretty much ended up in the same situation as Peter Dunne, only with more integrity and less willing to sell his support in Parliament to the highest bidder.