Actually, if the past two releases are any indication they're going to make core gameplay changes on the back side and with the defaults (pyro air shield as a counter to demo and soldier superiority) and then any unlocks will be gravy on top of everything. If you make it so you HAVE to have the unlocks to play as intended then they would've failed.

The problem with heavies without a medic is that they are slow, have short range, and are so damn big they couldn't dodge with their speed if they wanted to. They excell at getting up close and personal where their chaingun can mow down people, but to survive there you generally need a medic attached to your hip. In short, a heavy is like a bigger pyro, except with longer range and a spin up time.

There are a variety of ways you can change the medic dependency of the heavy and that could be by decreasing gun the spread slightly so they can be 'in play' from a longer range or to increase their short range deadliness so when they do get into the fray they can down their enemies faster than they go down themselves. Neither of which, BTW, are viable since they would be cumulative with medic+heavy combinations.

Three things won't change:
1) He'll have a chain gun that fires as a primary and spins up as a secondary (pyros were lucky as nothing was mapped to the alt fire which is now compressed air shield)
2) He'll have a shotgun.
3) He'll have fists as his melee

Heh, maybe they'll add a secondary to the default fists where you grab the enemy and use them as a shield. That'd definately be interesting.

The problem with the low health-higher damage idea is that with a medic you can stay at low health longer while under fire than you could solo. It'd be a cumulative affect since taking small arms and then getting healed will keep you pretty much at a static level of health and lock in the increased damage.