mousiopei think not having highlander as an option from the start its a mistake, sure it would be harder to get games running and to create a balanced system but it would be a much smoother transition from casual players to some sort of competitive format,sure its cool to hate on highlander here but if i actually invite a friend that never played anything except pubs and i tell him its 6s pretty sure most of them are going to decline the invitation but if i explain to them its just 9v9 (a glorified pub) i might get some of them to actually try it ! having options never really hurt anyone
Matchmaking will probably be more like a pub with 6 players on each team, some classlimits (because 2 demo/2 heavy/2 medic is not a fun game for anyone). and everyone actually trying to win and not being completely awful at the game than it will be like 6s.
I doubt a majority of matchmaking games will have a team with 2 scouts 2 soldiers 1 demo 1 medic.