I agree with this statement, however I am not sure what exactly a superior coin would look like. There are things Bitcoin lacks when it comes to anonymity, but it seems pretty sound aside from that, as we currently understand the technology.
Any ideas what Bitcoin lacks that future coins could do?
Bitcoin lacks anything that would make Average Joe want to use it imo. In addition to technical prowess, a superior coin would have to be actually useful for it to have a chance to dethrone Bitcoin. Trading them for Dogecoins or paying for coffee is not useful.