Looks like multihulls are out for the next cup, plan is apparantly to go with foiling monohulls:
Team New Zealand confirm 36th America's Cup to be raced in foiling monohulls

Team New Zealand have confirmed reports that the America's Cup is heading back to monohulls.

Luna Rossa boss Patrizio Bertelli, the Italian Challenger of Record, broke news of the move away from catamarans in an interview with La Stampa on Monday (NZT).

Bertelli said the return to monohulls, albeit radical foiling ones, was a condition of Luna Rossa helping Team New Zealand win the last America's Cup in Bermuda.