More usually with one of these intractable problems, it is not the theorem itself which has some important consequence, rather the method of proof.
The intractability of the problem represents some shortcoming in our mathematical methods, or some failure to recognise two fields or structures within mathematics to be equivalent to each other.
By the act of proving the theorem, some method is often revealed which can be applied to other, similar problems. Because of its nature, the resolution of the Collatz conjecture, if it helps in any way, will most likely extend our capacity to shortcut repetitive algebraic computations, increase our mastery of number theory and improve our understanding of how to solve some category of problems, which we generally find difficult now.