That's right, they will come and go often, as yearly fads, each new one with a new shiny gimmick, and people will be running after them chasing their golden opportunity to invest into better crypto.
You talk as bitcoin had been in place for decades. Most of the new and better cryptos are still in the process of establishing themselves. Some of them are only now coming out of the initial phase and are starting to have value that isn't dependent on bitcoin. This is the indicator that the crypto market is changing shape from a pyramid to a cluster. Bitcoin won't be at the top of the pyramid any longer, because it's only strength is the faith of the old adopters. And there aren't enough of these old adopters and the large majority of them aren't competent enough to push through this "U BUY COIN, ME GET RICH!!1" scheme.