Canada is automatically in the 2026 World Cup of Soccer as one of the host nations. I would assume all their first round games will be played in Canada. Could be 3 or 4 games depending on how they arrange the groupings with 48 teams. USA and Mexico also already qualified as it's a three country hosting deal with 48 teams qualifying up from the current 32. Don't confuse next years 2022 World Cup in Qatar which Canada is still trying to qualify for still.
According to the wiki page above Montreal has definitely dropped out as a host city in Canada. Now only Edmonton and Toronto left. Not sure why Vancouver is not in on this unless FIFA demand grass fields. BC Place or whatever it is called now could handle the seating capacity requirements easily and soccer is popular in British Columbia. Seattle is hosting games, why not Vancouver? Dropping the ball somewhere there it looks like so far. The exact cities hosting I think can still change until a year or two before the event, so this is not cast in stone quite yet.
BMO field it states in the WIKI website will be expanded to 45,500 seats temporarily for this tournament.