I agree about not putting the sport behind a paywall, for the various reasons given above. I certainly wouldn't subscribe unless it was something very cheap (I'm talking maybe £50 or less for a year, not £40 a month).
I do think there is maybe room for a subscription to watch all of your clubs matches, or perhaps even all of your clubs away matches, if you're already attending home games. I would have thought that sort of thing might interest some fans. It's a bit more targeted than paying to watch all SL games.
I assume it would have to be agreed with all broadcast partners (including Sky).