Hmmm.. Considering how rediculously pathetic the coming generation is, AND how physical Rafa's and Murkovic's games are, I would really advice him to keep playing for quite a while yet.
Seriously. It's no impossibilty that the mentioned players' bodies will break down sooner than Roger's will, despite the fact that Roger is 5 years older. And if that happens, Fed could easilly turn back to being the superior #1 again, aged 36-37 for quite a few more years, and end up in the high 20s, slam counting wise. Maybe I'm just dreaming. Haha....
Rafa: "It was an honor playing with you too, John. Thank you."
McEnroe: "Thank you very much... For lying..."