Realistically, given the global economy plus the vast increase in communications capabilities, should people just give up on Esperanto, and let English become "the" lingua franca?

Latin used to be the official language of a large part of the ancient western world, along Akkadian, Aramaic, Koine Greek, Persian, et al. at different times and in different locations. No doubt English will either morph into another language or be replaced by some other contender.

Ceci n'est pas un seing.