I think the next ETF will be a Solana ETF, and we know how beneficial the ETFs were to bitcoin's value.
I don't think ETF of other altcoins will have any impact in the price. It is all priced in now.
We can see the case of Ethereum ETF. The ETF was approved shortly after BTC ETF, and the price simple didn't move.
This will probably happen again with SOL.
I am a bit skeptical about SOL, because I don't think memecoins are worth anything. And as a memecoin platform, I don't see much future in sol.
The best projects are still in ethereum, like AI coins for example, and memecoins all go to solana