CAF (Africa): Nine direct spots + one inter-confederation play-off place
Concacaf (North and Central America, plus the Caribbean): Six direct spots + two inter-confederation play-off places
CONMEBOL (South America): Six direct spots + one inter-confederation play-off place
OFC (Oceania): One direct spot + one inter-confederation play-off place
UEFA (Europe): 16 direct spots
The three host countries will automatically qualify for the tournament, thus occupying three of the Concacaf slots.
Firstly you divide that into 4 teams of 16 groups, or you could even make 8 teams and 8 groups, which would be awesome. Then you have 32 teams left, which will be knock out stages but instead of one game, it will be like UCL where they play two games each, and then 16, and then quarters, then semi finals, all two games against each other, and then just one game finals.
That means teams would play probably 12 games until the end, or could be even more if we do 8 teams and 8 groups, but I do not think that makes sense. So that means 12 games would be the case if you make it 64 teams. Of course you are not going to get everyone be awesome, you may not end up with 64 great teams, but it will not be Sri Lanka level neither hence I think it would make sense to have this many teams.
The more the merrier if you ask me, more fun for everyone.
More teams equal more games, hence there may be many blowouts. Nobody finds that interesting to view. Indeed, greater income and more worldwide engagement, but at what expense? The World Cup's supposed to be the pinnacle of the sport. Diluting the quality for the sake of inclusivity could backfire.
More is not necessarily better. Maintaining the reputation of the tournament should take front stage. So be it, keep it smaller and more competitive if it means so