Depends on if you think modern politics is truly defined by swing voters or if it's more about getting people on your side to actually turn out and vote for you. The former is certainly the traditional view, but I think the latter is more accurate. Hillary banked a lot on support from "Never Trump" republicans which never materialized.
I'd invite you to read this article.
An Unsettling New Theory: There is no Swing Voter
It mentions people who were never going to vote for Trump but voted for a third party, as well.
I do disagree with what's mentioned in the article about the person nominated not actually mattering, though I'm not sure if that's just author of the article's interpretation. I think different candidates can motivate people to come out and vote more than others, and appealing too much to "Never Trump republicans", for instance, can have a negative effect. Triangulation might have worked for a brief time in the 1990s, but the time for that is past.