Items may make a return in the competitive smash scene. It all depends on whether the community blindly bans them or not. Melee tournaments actually began with items, but they were removed as explosions started skewing results in key matches. If items did not explode randomly and had more constant spawn locations/rates, they would still be in tournaments.
Banning anything (items, stages, etc.) is a delicate art, and one has to understand what adds depth to the game and what tips the scales too far in favor of someone or something.