I don't think Elon Musk will popularize Shiba like Dogecoin. Indeed $ 20-$ 40 is nothing when calculated with our daily needs, but there is another value that must be taken into account behind the figure. If you compare Shiba with Doge, it's not right for me. In terms of categories, Shiba and Doge are clearly different.
Elon Musk is a smart person in my opinion, of course he has views that I don't think are comparable to the way we analyze the future of coin.
Both Shiba and Doge is same, its only a community coin/ token, but Doge is older and also have its own chain, so Doge value probably would be higher than Shiba, but who knows if Shiba can keeps grow and passing Doge in the future.