It could be doable soon in some places, but some things to keep in mind. Transporting such a massive stage to the US, is incredibly expensive, and it wouldn't be worth doing so, if they can only confidently sell out 3-4 stadiums.
Then you have to remember, Musers are crazy. Toronto x2, MSG x2, Bell Centre x2... How many of those who attended probably saw both nights? Probably a fair bit! ACC is roughly 20,000 people.. The Rogers Centre (Stadium) next door is roughly 54,000 people. Now you need 54,000 individuals, not 20,000 x2 where a good percentage are the same person seeing both nights.
Also, I don't know about the US, but our big stadium for Music is Rogers Centre, which is a Baseball stadium, not a Soccer stadium, different shape and such. Possibly requires a different stage design for the field shape/stadium seating shape?
I'm sure it is something that'll happen, but I think they need another big US album release, to build a bigger popularity, where they can sell out stadiums in more places confidently.
It would also be a weird tour system... Would they still tour NA arenas, then come back and play Stadiums in select cities? Would they Travel two stages as once, playing Stadiums where they can, arenas where they can't? That would feel disappointing for fans in the smaller areas that don't get a stadium gig.