My guess is that MDG will chose Mobservable over Rx.js, It’s easier to reason about for people not used to FRP. And I agree about Blaze 2, I guess we will see some mixins to ease the Meteor integration but that’s it.
I’m currently using React on all of my meteor projects and I won’t miss blaze too much. It was nice but the mainstream React ecosystem is a big plus.
React-native is also a nice feature coming along, it’s a bit more work than cordova, especially on Android, but the gains are huge.