Take the example of Tornado Cash, although it is defunct now, it is able to gain popularity and traction because it is utilized.
Market cap is nothing if the coin in question doesn't provide any real use cases to the world. It's just a means to measure a coin's value relative to its circulating supply. I don't think making Shiba Inu a privacy coin would be any help, especially when governments are taking a tough stance against crypto/Blockchain tech (mainly the USA). If developers add privacy features to SHIBA, it would be optional instead of enforcing it across its users. Something like DASH is doing right now.
Maybe SHIBA holders will be able to enjoy privacy by sending their tokens to a mixer? You can bet market prices will rise if new features are added to the "meme" coin. At least, the ride will last for a short period of time. Don't expect SHIBA to get that far because of the many coins in circulation. Who knows if it never gets to $0.01? Just my opinion