OK I thought of ingenious way to create such tournament. Looking into my country's tournament there are 8192 participants with up to 13 weeks go cup matches. It begins in the 1st week of the new season and ends right around the playoffs so knowing that 13 weeks of cup competition from national tournament is possible, so would worldwide competition.
With that being said, given the new format would take the top 32 teams that win, 16 teams that rank from 33 to 48 would fall into that worldwide cup competition just like those that fall from UEFA Championship to Europa Cup. Not all the losers from B3 will qualify but then again not all the UEFA CHampionship losers participate in the Europa Cup. The new format has 8 games before the 32 team single elimination round meaning those teams cannot fall into the new cup tournament until week 9.
With 16 teams from B3 mergining to the new cup, there will be total of 32 teams, the other 16 would be participants of the tournaments that made it through the first 8 weeks of the cup. The tournament would start with 4096 teams and the following table shows how many teams would be around on the right side and the correspondent week on the left:
9...16
8...32
7...64
6...128
5...256
4...512
3...1024
2...2048
1...4096
In week 9 with the 16 extra teams coming from B3 then 32 teams would be competing on the 9th week which would fall down to this table shown below:
9...32
10...16
11...8
12...4
13...2
the 13th week would be the final with 2 teams left. Here is a way to get 4096 teams in addition to the 144 B3 so that would come down to 4240 teams havings a worldwide involvment instead of 144. I haven't thought of yet how many teams from each country and who will be a part of the tournament yet. But you can guess big countries like spain for example would have like 16, and all should accumulate to 4096. I would think of number of involvers that can easily be discussed and figured out but for now acknowledge the new format I'm proposing as a very real possibility