This won't be a real Twitter competitor until they allow lists. Once they do that, Twitter is toast.
But I'm not optimistic. I have a friend who's a product designer at Insta and have mentioned the need for lists for several years, and he acted like it's the first time he'd heard the idea. 🤷♂️
I don't really get this logic. Leave a social network that is already setup for things like that for another one just because they add a similar feature too?
Most people are going to use the service that has the engagement they are looking for. Some won't use Twitter because they have a deep disdain for Elon Musk. Some won't use Threads because they have a deep disdain for Meta on the whole. But most people will just use the service that works best for them. On inertia alone I highly doubt there is a mass exodus from Twitter anytime soon.