I think this article is very interesting and I do agree that you can figure out most of the major players 5 years out — and things get even more clear after the election.
I would point out that each of the past few elections brought someone who wouldn’t have been noticed 5 years prior being a decently sized player in the election. Here’s a list:
2020: Pete Buttigieg (South Bend Mayor) or Andrew Yang (businessman)
2016: Ted Cruz (Private Lawyer, Fmr. Texas Solicitor General running for Senate)
2012: Bachmann and Herman Cain [this year was harder to do]
2008: Barack Obama (State Senator running for Senate)
2004: Wesley Clark (NATO commander)
2000: Alan Keyes (State Department Assistant Undersecretary)
I could go on and on, but I think we should also expect at least one person who is WAY off of our radar to make an impact in the race along with the usual suspects in this article.