The one problem I see with 4v4 is this:
If FIRST advanced 8 alliances into the finals it would mean 32 teams in the finals, some regionals don't even have 20 team attending. So maybe FIRST is thinking 4 alliances of 4 teams each for the finals (16 teams in the finals).
At
Battle at the Border 2005 we did not have 24 teams so the finals consisted of 4 alliances of 3 teams. Is there a similar rule for regionals?