> The question is ‘when’.

Why ?

In the 60s we thought we'd be living on the moon and mars "soon", flying cars were talked about seriously, that faster than sound jetliners were just around the corner, &c. Sometimes what's possible isn't desirable, or what's desirable isn't possible. No one went back on the moon, space programs are basically dead, planes are still as slow as they were in the 50s, a 747-8 from 2008 isn't much faster than a 707 from 1956