In the eighteenth century, there were no concert halls.
In 1750, no one would have asked: “Who will write the next great enduring symphony?”
Venues develop in response to art, or art and venues develop together in some not entirely explainable relationship (like instruments and music). Halls are instruments too.
Can anyone doubt that the 2,000-plus-seat Musikverein/Carnegie/Concertgebouw model is a period piece? It’s a manifestation of a repertory and a society — linked to a time, linked to time. This kind of concert space can survive, but not as a norm.
And we should not be waiting in Festival Hall or any such place to hear the next “big thing” in terms of new music. It may not be big, and certainly it will be happening elsewhere.