Players that I think will improve to a higher level include Andy Murray, James Ward and Dan Evans.
There has been threads where we guess end of year rankings for players though, and most tend to be woefully out. Very few players seem to overachieve from these shores, more a case of not quiet living up to your high hopes!
CF because he's clearly underranked since he's got all his points in a few months; MW because (from what I've seen/heard of the GBR youth) of all the young guns I think he has the most room for improvement.
I think Murray is due a form slump so I don't know how much he'll push on next year. My guess is that he will pass Nole as some point but not Rafa or Fed - but some other youngster will probably have a purple patch in the summer and contest 3rd with him.