Outside chance, but his next goal after taking the Slam lead ought to be the total men's singles titles (Connors record). He could win maybe 4 more titles this year (let's say), which would put him at 88, 21 behind Connors' 109. Three years of 7 titles or four years of 5-6 titles could get the job done.
He doesn't really play them. My meaning was for him to continue racking up more titles in general. Four slams plus usually about 7/9 masters plus ATP Finals is 12 tournaments a year. He historically, since 2011, has participated in only 2-3 ATP 250/500 tournaments a season, so that means about 14-15 tournaments a year, something that's doable. He can rack up 5 titles a year on that schedule.
I think his only goal right now is to break that GS record. I'm pretty sure he will retire right after Fed and Rafa if he holds that record. Motivation plays a huge role in his game and these two rivals motivate him to play this good.