You think Shaco would be a good hero 3v3? Obviously it's all speculation but it seems to me it will be all about the beefier champions who can also do dmg. I.E. Nunu, Kayle, Chogath, Morgana
Of course, maybe it will work the opposite as it won't be quite as easy to target a squishy and burn him down in 4 seconds.
Shaco has a lower HP gain that Evelynn yet is infinitely more survivable than Eve. Stacking tanks never works because early game they are the hardest heroes to get kills with alone. Morgana is really more of an off tank/stun support hero.
Kayle can slow and attack at ranged with increased damage. All you really have to do with Shaco is build attack power and get her in one good fear forcing her to blow her ult and kill her. I think heroes with escapes and survivability will shine more, along with heroes with mobility (teemo).
The only tanks I see doing REALLY well in this environment are Rammus and Malphite, since both have good survivability and control along with the ability to scale their damage very well through gear.
Malphite, Shaco and Taric would probably be my choice of teams. In any case, it is all specualtion.