How insignificant is Georgia to this Presidential race? It's the mirror image of Michigan, a state which the Democrat must have as a decisive win to have a real chance at the Presidency. The Senate seat will matter more in Georgia.
I wouldn't necessarily say that. Obama could have lost Michigan and still won very comfortably.
However, I suspect you meant in a scenario where Ohio and Florida were far from guaranteed, then yeah, losing Michigan would be very risky. But there are a lot of alternative paths for Democrats to take for an EC win.