I don't think 60 will do it. There are at least three to five (depending on the issue) unreliable Republican votes in the mix: Snowe, Collins, Chaffee, Specter, McCain.
The Democrats never got more than 62 Senate seats at the height of their power. Realistically, the GOP is never going to get more than that number if they win ALL the seats in Red States.
Unfortunately two of them, Snowe and Collins, are from Maine and will win easily if they choose to run again. It's either them or dims - not much of a choice.
The once great and conservative state of Maine is now so blue it will take decades to change. Retirement to a warm red state is my only option - sad but true.
All whom you mentioned vote to end fillibusters.
And McCain hardly belongs in that group. His voting record is actually quite conservative, in spite of some retohric.
Please note post # 5. This is so predictable. If the GOP does not deliver they will lose seats. Case closed.