I'm going to go out on a limb here with a prediction. Reactive Programming will not catch on in any big way. Maybe in 10 years I'll look foolish for having said this, but I'm willing to take the chance.
My bet it's here to stay.
A "standard for mobile developers"? Not that I can see.
In just about every event-loop-driven, there exists an implementation of Rx (or something like that anyway)
You sure about that? I certainly recall plenty of holy wars over object oriented programming.
What do you mean by "this"? RAD tools like Visual Basic, Delphi or Cincom Smalltalk were event-based - which is also true with most native GUI frameworks, BTW - but they did not provide any abstraction above the level of events. Reactive programming takes events and stuffs them down a set of pipelines, where previously you had this giant switch statement for dispatch and the logic for actually doing something was split among some of the branches of that switch. Now you can group your logic around a certain pipe, which allows you to see a complete description of complex processes at a glance, without the need to guess "which event is used as a next step of this process?"
So Reactive is actually a quite convenient interface to event-driven systems and it wasn't available in RAD tools of the nineties (if memory serves, might be wrong on this?)