This would be an absolutely shit idea, and you only need to think it through for a minute to realise that.
There is no sporting value in excluding Barcelona in order to include Tre Fiori, champions of 55th placed country San Marino. There's absolutely no point. No one would watch it, they can't host a televised game, good players would be injured by part timers and it would be a double figures scoreline.
Bayern smashing through the champions of Albania, Belarus, Malta and Hungary before finally getting a half interesting draw in Ajax or someone is just a shit tournament.
There is a very good reason the old European Cup format was ditched and it's because most of the games were foregone conclusions - and that was 35 years ago when some Eastern European club having a 50,000 seater stadium made them a rich club who could compete with the champions of Germany or Italy
And by the way it would absolutely ruin all those domestic leagues, because whoever got into the first edition would get so much money, they'd never be caught - which is what's already happened in a bunch of the smaller leagues who get CL places.