He's obviously executing better than he has been in the past few years, but he still has to be playing well enough, putting well enough, to win against the younger players. Same goes for Phil for that matter....
It's not gonna be easy for him, providing that he's playing well even... but he's in a much better place competitively than where he was just a few years ago.
If he can win another major - it would be an enormous achievement.
I still feel comfortable in assuming that Nicklaus's standard of 18 majors will not be in jeopardy. Not by a long shot.