STR: fighters, wardens, barbarians, 2-weapon rangers, some clerics, some paladins, warlords
DEX: rogues, archery rangers
CON: infernal pact warlock, sort of half-ish for starlocks though I still find its more CHA-based.
INT: wizards, artificers, swordmages
WIS: Clerics, paladins, invokers, druids
CHA: 1/2 (more like 2/3) starlocks, feylocks, dark-locks, bards
I didn't list everything of course but con would still be at the bottom. I understand some wardens could add CON to AC but that still doesn't make it a primary stat like the strength does. Now if you don't have a +2 to str for your race then maybe you decide to focus more on the CON if you have a bonus to it instead. But still it's about hitting and making your powers and effects go off.
Right now my hope stands on the legs of the sorcerer. Everyone still mentions the "wild magic" sort of thing that was talked about in early talks about the sorcerer. To me that just exhudes of CON-based powers. I'll be disappointed if there isn't at least a build that uses CON as the base stat for my favorite caster class
PHB
Fighter: Used for Hammer/Axe feats, hammer/axe powers, and several fighter feats. Battlerager fighter uses Con for many powers and their class ability.
Wizard: Used for Staff Defense. I believe it should have been used as a secondary for powers as well, but they really only tap wisdom for that for some reason.
PHB2 (so far)
Barbarian: sub-defender barbarian build uses Con for many powers.
Bard: Melee bard build apparently uses Con (making the Half-Elf "thee" melee bard).
Druid: Caster druids use Con for a sub ability on some of their powers, and get AC from Con.
Invoker: One invoker build uses con for powers.
Warden: More striker focused warden build uses con for powers and AC.
Con as an attack stat is difficult to justify. It would work for a class whose power is innate (breath and poison attacks should be con based). I could envision a class who had a lot of retributive attacks be con based (unarmed attacks hurt the attacker, fists break on your tough muscle).
I actually don't like Infernal Warlocks using Con in my games, and we are currently considering switching their attack stat to Charisma as a house-rule for our group; our group doesn't like that tieflings make better starlocks than infernalocks, but we need to make sure that effectively reducing their HP doesn't make it harder to play them the way they were meant to be played (we might switch their secondary from int to con and give them con to AC if that's the case).
I think you're missing out on how important Con is to many classes as a secondary stat:
Yeah, I think/hope the Sorcerer will be Cha-based, with Con as the second most important.
Con as an attack stat is difficult to justify.
It really isn't.
CHA: you're using your force of personality to wack things.
CON: You're relying on your body's ability to withstand the forces being channeled through it.