You only need to listen to their (broadcasters) desire to move towards 8pm Sunday games, which would be awful for supporters, to know they're not concerned.Yes, as I understand it, It’s not even about preserving attendance at top flight matches. It’s mainly for the benefit of attendances lower down the pyramid, as you mention.
But the traditional Saturday 3pm kickoff has been so bent of shape, and continues to get worse with every new PL TV deal, that we’re getting to a point where pretty much every match will be available to be televised in the UK, anyway.
The FA are even happy to play FA Cup games at ridiculous times (how many third round kicked off at 3pm?) for the sole benefit of foreign betting markets.
The days of the Saturday 3pm is being demolished at the top tiers of the game, but the blackout does at least to some extent protect the lower leagues.