Thing with Federer this year is that not only his record is bloody good, but apart from a very few opportunities, in most of his matches the winner was never in doubt. Exceptions are obviously the five setters at AO, but after that only the Berdych and Kyrgios matches at Miami. So this is real dominance, not just a "great run".
It is true, however, that a similar statement can be made regarding Nadal, either. The only guy stopping him this year is Federer (he only has three losses for the rest of the field). His only non Federer loss on HC was against Querrey in the Acapulco final -- so maybe "vulnerable" is too strong a word, at least against the field. He has won with authority too. Correct me if I am wrong, but his only two match wins that hang out in balance were at AO, against Zverev and Dimitrov.
So everything points to a few more Fedals in the North American HC´s. By now Nadal already knows that, yet again, Federer is his main adversary (as far as 2017 goes). He will surely come with something new tactically wise in Montreal. My guess is that it will be on the serve department.