The issue for sky and BT is there is no audience at 3pm Saturday. They don't want it.Its actually bonkers mate.
The other thing is the blackout only exists really in the UK for the PL.
In most of the other Top European leagues there is no blackout and their footballing pyramid hasn't collapsed.
A lot of PL clubs, even Championship clubs have a waiting list for season tickets or fans find it hard to get tickets - how can these willing payers see their clubs game - when no one wants to take their money.
Their core audience will be at games. Granted there will be some sort of audience but nowhere near enough.
It's not like abroad where the viewers have no chance of going to games.