Most of the YouTube shorts that I see are Tik Tok videos already, but uploaded to YouTube as a Short.
I don't think YouTube added Shorts to take out Tik Tok, but more to combat their bread and butter audience looking elsewhere.
We have seen a few tech giants be devoured, so I would never say never. Vine sure died quickly for example.
I have not used either platform from a business perspective, so I have zero skin in the game.
Personally, those short videos can be a huge time suck.