Final four tournament has always been a terrible format and unfair to the clubs that actually won a goddamn trophy for the past year, it's pretty much as stupid and pointless as one team (for example Juventus) winning both the title and the cup and having to play for the Super cup against a random nobody who ended up empty-handed in the last season...
Final six is a better and more fair idea, where the actual winners are seaded in the semifinals and the rest of the four random trophyless nobodies has to play each other to determine who qualifies for the semifinals to play against the actual winners.
Also, when a team wins a domestic double they should qualify directly for the final, they won their place there.
Teams for the final 6 tournament that didn't win anything should be determined by their final league position, the runner up in the Copa final and possibly the previous title and cup holders or whatever, it would be fun and fair if there are 4 different teams that won a title and a cup in a two year period and they are joined by another two different clubs that ended up losing the two cup finals in these two years.
If or when there are teams that fit more than one of those criteria then a spot in the tournament goes to the next best placed team in the league or whatever, there are several options for constructing a fair and interesting format.
Also, all those games should be played before the start of the season, it would be great for the teams preparation for the new campaign and also that should cost the plane crashers and journalist assassins way more than 200 mil for 6 years...