Please change the Majority System before you release All For One.
Nothing kills game modes than these faster than the inevitable 3-groups hijacking the Champion Select for nearly every game the day after release. I get you want to reward grouping and likely won't just outright delete Majority so...how about a compromise?
New Majority System: If you and your pre-made Teammates vote for the same champion, you gain a +3%, per extra player, priority weight on the decision roll.
Just to display what this would look like.
5 Randoms: 20% chance per vote. 3 Randoms, 2 Pre-Made (Same Vote): 43% Pre-Made (40 Base + 3 Bonus), 19% per Random Vote 2 Randoms, 3 Pre-Made (Same Vote): 66% (60 Base + 6 Bonus), 17% per Random Vote 1 Random, 4 Pre-Made (Same Vote): 89% (80 Base + 9 Bonus), 11% per Random Vote 5 Pre-Made: System reverts to 5 Randoms voting.
This still gives grouping a statistical advantage without completely screwing over people who just enjoy playing the game solo. Soloists need agency too.
Edit: In hindsight you could just apply this to the voting system as a whole rather than making it specifically Pre-Made too.