Well, now that Pokemon can finally be on home consoles, there's not much stopping them from having the visuals of Battle Revolution, if anything it could be even better since it's more powerful hardware.
As for being easier to make, it doesn't mean worth it to make.
It's not like there's anything stopping them from making unique mini-games aside from, they don't want to, especially now that they have the power for that.
Having a game that was just battles made sense because you lost the whole social element of Pokemon, but now that the Switch is capable of being played on the go, a game that's just battles would just feel very gimped. I could understand something along the lines of Coliseum or XD, but anything else just wouldn't work.