He does think we will see $30 Trillion come into the Bitcoin marketcap once this does happen. https://beincrypto.com/grayscale-sec-ceo-approve-all-once/
$30 trillion being shifted towards BTC? Did he mention a time frame for that? This could mean anything if someone throws out a number without saying what time frame they are talking about. Long term I think it will be a lot, but I realize when I say long term that even this time frame is hard to estimate. I guess so far I have been wrong more often than not, but $30 is rather 10 years away than 3 years away would be my guess. $30 trillion is more than double the market cap of gold and while I believe that a lot of institutional investors understand that BTC should be part of their portfolio, we are still talking about a portfolio. It is not like everyone will sell their gold and switch to BTC.
To come up with some numbers here, the global wealth was around $454 trillion in 2022. I don't know what the breakdown is in terms of real estate, cash and cash equivalents, etc. I found some info that real estate is about half of global wealth.
But in order for $30 trillion to go into BTC, that means over 6.5% of global wealth would be put into BTC. I doubt that this is going to happen overnight I believe that BTC will become a very powerful asset class, but it still means that people have to give up on one class in order to shift their wealth into BTC (they can of course produce more wealth overall and use that). For the sake of diversification, most actors will try to strike a balance they deem reasonable.