Absolutely everything depends on your actual needs.
The capabilities of cameras continue to improve over time, although it looks to me like the rate of improvement has slowed considerably.
Here's the thing: while the cameras have been getting better, the needs of photographers have probably not been changing all that much. Instead, the additional capabilities remove various crutches that were previously used to achieve acceptable results (e.g., the use of flash instead of high ISO).
As a results, the natural question has to be raised: how much is enough?
The 5D3 is unquestionably better than the 7D in terms of high ISO performance. It had better be, because it's both full frame and newer technology that comes at a substantial price premium. But that's not the real question that has to be answered.
The real question that has to be answered is: is the 7D good enough for someone's needs? Only that person can answer that question, but as cameras improve, the lower end will fulfill the needs of ever larger numbers of people.
Some people simply have to have the best they can get their hands on, no matter how good or bad that might be, usually for irrational reasons. For the rest, though, there's a point at which a camera's capabilities are simply going to be good enough.
I suspect the 7D is right at that point for most people.