Barismo in Cambridge does (or did) a "hot draft" coffee, that is always on tap, is delicious, and is remarkably like hot cold brew. Their method is apparently a secret (although I'm sure more digging could find it), but I wouldn't be surprised if it wasn't basically on-demand heated cold brew. [1]

1. https://www.baristamagazine.com/the-function-and-future-of-b...