Yes 3v3 is the minimum to play. 5v5 is the ideal for fun factor and strategy as I understand it.
With the current group of people that are assembling it appears they will be shooting for weekly meetups on Wednesdays. I think the hope is that by establishing a specific day of the week to always meet up then opportunities for drop in play are higher if you plan to hit those days? and guessing also that as teams form or draft leagues start then people will be able to know when to plan to play.
That will obviously be the largest challenge with this cab. Need foot traffic and planned excursions until it hopefully takes hold.
Based on the number of people that have reached out already, I am very hopeful we will see 4-6 teams form and some fun/friendly matches shortly after it arrives.
It is obviously a large risk/experiement to see if this can take off in Madison, but what the hell... you dont know till you try.
I agree with you that the best upside is more return of the "arcade" vibe.