You've chosen a strange grouping to represent American libertarianism. When I think of American libertarian intellectuals of the 1960s and 1970s, the first name that springs to my mind is Milton Friedman.

Predictions are hard, especially about the future, but I doubt that the names and works of the likes of Friedman, Buchanan, Coase, Becker, Fama and Lucas (and, yes, Rand) are going to be forgotten or fall into disrepute any time soon. They have given birth to entire schools of thought (e.g. 'Chicago School' economics, Law & Economics movement) and institutions (e.g. GMU). There also appears to be no shortage of current libertarian intellectuals, and there appear to be more libertarian or libertarian-influenced politicians than ever, at least in the Anglosphere.

You appear to give no reasons for your predictions of decline for libertarianism or transhumanism. That is unfortunate.