I mean, in the fighting game world shit like that already exists. Ultra Street Fighter IV was still Street Fighter IV even though by time they got to the 4th version of the game it had a lot more content.
Compared to SFV which was 100% new engine, models, animations and play style.
It's hard to consider Nintendo unique snowflakes if they're just adding onto the Smash 4 skelton it's an enhanced port/xpac to the game. You don't see ASW claiming each new version of GG Xrd which has new characters, stages and stories to be a new entry. Just another expansion onto the game.