If anything, it's going to keep getting harder for Nick.
As Fed explained: Nick's not out there beating people with a once-in-a-generation serve. It's just a strange look.
Yeah, he serves well. But the big issue the best players had in early matchups with him was the timing. He has a quick and unusual motion, and it was obviously trouble for the best players to get a read on it over the course of a single meeting or so. That's why he came screaming out of the gate with huge wins over legendary players, and set up these huge expectations that he never had the game to come through on.
But over the last year or two, the good players have gotten on to it. Fed's getting to him now. Nadal's won four out of five. Murray's never been troubled by him in the slightest. Nor Dimitrov. Shapovalov handled him right out of the gate.
Once that edge is gone, what's he got to rely on? An overrated, error prone FH? A push BH? Subpar movement? Non-existent fitness?
I expect a huge uptick in tanks and hissy fits as this one trick pony starts to come to grips with the fact his one trick has been figured out, now that he's been around the big boy block a couple times. As the more talented young guns also start to figure him out (Zverev, looking at you), the bloom is really going to come off his rose, I fear.