Will Wigmore Hall's new private funding model convince Britain's wealthy elite..

[Nearly Sane]

... to rethink how we should subsidise the arts?

I suspect that arts subsidies, whether as regards the 'elite' or not are going to be a subject of discussion in the election, though that will likely concentrate on the BBC, and beyond.

https://www.classical-music.com/articles/wigmore-halls-new-private-funding-model-rethink-how-subsidise-the-arts