I don't think Harmy will want to leave the North-East at all and I very much doubt any other county will want to offer decent money to a bowler in his mid 30's who doesn't play any limited overs cricket and who's body is falling apart. I think Benks will want to go out on a high and any trophy success this season could be that, otherwise I don't actually see any big earners leaving the county.
I agree about Harmison in that respect but I think he might draw a line under it at the end of this season, his fitness isn't going to get any better.