Takes 3-6 months to learn fluently, and a lifetime to find other speakers. ;-)
Maybe in the next 100 years, some neo hippie collective of a not insignificant size decides to make it the preferred language of their community. It’d be cool to walk into a part of a city where Esperanto is the norm, like Chinatown or the Jewish neighbourhood.
For government functions live translation is something skilled translators can do pretty easily, and for common folks, live machine translations is getting better and more accessible.
I for example read many tweets written in languages I don’t understand. And I think it is only a matter of time before other social platforms (including GitHub and HN) catches on to provide accessible translation tools so people can read and write in their native language, and have machines translate for them.
As for communicating face to face, surely there could be a device (or more likely a phone app) that does that, but mostly I think people will just continue to learn an auxiliary language or two and find a common language to communicate in, only using the translation app as a backup in emergencies.
The grammar is mostly regular. It seems like the thing a stubborn introvert likes: You can hardly use it anywhere, but it has nice properties. And unlike Lojban, Esperanto is something you can learn to fluency fast on your own on the internet.
I've met one such.
His parents met at a conference, and only had Esperanto in common.
I've been at music festivals where I met people who did not speak English, so Esperanto was our best common language.