What I was wondering, is it possible to have for example an input action bound to a function and later to another function? Like the function pointers in C++
I’m not sure exactly where this would be a feasible solution, just wondering if it’s possible 
In a nutshell - “no”. But aspects of Blueprints can of course change like for example variables or you could create instances of blueprints on the fly. C++ is very powerful, so it would give you more flexibility. Blueprints are kinda “working around c++ with a load of bandaids”.