The problem is not and will never be the competition. It is tripping over their own feet. Just make your systems feel not awful and allow the game stand on its own as something fun to loop seasonally. This gimmicky nonsense of making the SB a god tier class in its debut season marginalized every other classes attempt to progress its build in end game. There are some fundamental issues with the games systems, mainly end game progressions, especially in Season 6 that make the game feel like it has no cohesive vision for what it wants the experience to be.
Completely changing how things that feel bad work from season to season but not making it better is going to fatigue a lot of players into not wanting to bother anymore. Season 6 was very discouraging. Learning the new stat squish and changes to where components are leveled all over again only to get deeper into paragon to realize the new changes feel like trash. This is in my opinion only of course.