Another thing, remember when Madara was transforming into Kaguya and Naruto ran towards her and Sasuke teleported? If he had to swap with something, something should have been left behind (substituted into) from where he teleported, yet there was nothing.
exactly, his jutsu so far has shown the ability to
1.teleport people like he did to madara and kaguya
2.teleport himself like what he did when he grabbed narutos leg and your example.
3.shifting through spaces utilizing an object he sees like what he did with sakuras jacket and his sword which impaled madara
logically thats what it shown, its a s/t jutsu so it makes sense. same with other s/t jutsu
kamui can
1 make obito go intangible
2. allows obito go into a dimension, and warp people there
3. can warp people in long range
ftg
1. teleports the user freely with seals
2. with two users, you can swap an opponent with each other like what tobirama and minato did
3. can teleport people around connected to the users marking or chakra etc.
so sasukes jutsu has variations just like the other two s/t jutsu, its logical and what he said to obito practically confirms it.