Really, it's only Lendl and Connors now that he's competing with, aside from Sampras going 10 years and 10 months in the top 10, (and that blasted 7 wimbledon) and Agassi's match wins in the ATP tour era.
He has a shot, if playing well, to match Johnny Mac's win percentage too.
Edit, just tied Agassi with at least 46 wins at all 4 slams. Lendl is two away at 48 (wimbledon and the AO).
After that, the only one left is Connors, who's the all surface champ with 59 clay wins.
He's also 9 wins at the USO from Johnny Mac, which would make him top 5 at all 4 slams. Also never has been done before. Agassi came the closest, falling 5 short of Borg at Wimbledon.
He needs 10 more wins at Wimbly and 9 more at the FO to be top 5 in all surfaces, passing Agassi at 5 (52 clay wins), and Edberg/Vilas (65 grass wins). Also never been done before.
I like that 48-at-each-slam record, hope he gets there here. He could probably lift it to 55-60, perhaps beating Vilas's 56 FO wins in the process. Connors' 233 is also a nice one, though in this case eras are difficult to compare. Nonetheless a very significant record.