In 30 years, a lot can change in the global economy and, accordingly, the purchasing power of the dollar itself can greatly decrease. Accordingly, with the cost of a loaf of bread at $100 and the cost of BTC estimated in millions, then I wouldn't be surprised if Shiba Inu would be worth $5.
While you are right in that, in 30 years, I think 90% of all crypto that exist today will already be dead and abandoned. And personally, I think the chances that Shiba Inu will still exist in 30 years are close to 0. It is just a memecoin without any real life use.