I've not heard any rumours.
It is a strange anomaly given the number of pax that fly from BRS on other routes that it can't get a Toronto service.
It has been unlucky of course. Some of the past carriers that did fly the route went out of business: for example Odyssey Air around sixteen years ago and the most recent, Canada 3000, that had absorbed Royal Air, the previous operator.
Perhaps the loads from BRS were poor and caused these airlines to fail. Only joking because I seem to recall load factors were actually very good. Before anyone mentions it, I know about the importance of yields but I have no access to them of course.
These flights had to operate the outbounds via another airport (GLA in the case of Canada 3000) because of the runway at Lulsgate.
However, the weekly Toronto from EXT operates via another airport (BHX from memory but could be wrong) so that presumably is not a bar.
Incidentally, the last time I looked there were two Toronto flights scheduled from EXT next summer, both at Wednesday lunchtime - one flight to Pearson Airport and one to Hamilton Airport.