2 months ? .... it took us 30 years for futures and promises .... the observer pattern is from GoF :D ... chill ... mainly these changes are hyped and not real. We still don't have AI just "supervised AI" and a lot of BS for money :)
Same as the cloud and so on, those are old concepts we just reframed so we get money for them. Reactive programming was done in the 70s, functional programming is from the 1930s (Lambda calculus).....
unless you're working bleeding edge (which you shouldn't anyway, you can read up on what you need)
if you are 2 years away, that's something different but even than it's manageable as long as your are willing to learn.