You can go with the Diode [1] library for an Elm/Redux-like architecture. And with that you don't need to all the way down to cats or scalaz (although you sure always can if you want to).

[1] https://github.com/ochrons/diode

Take two average JS programmers. Hand one of them the Elm docs, the other the Diode docs. What do you expect will happen?

Both will continue using typescript/redux/react combo. Scala.js mostly makes sense if you are already familiar with scala, that's hardly surprising.