One, I'd say its pretty early to start projecting 2020. The two best prospects for that draft at the moment are both wingers right now in Lafreniere and Holz. Most of the centers you are waiting to see if they can successfully play it at the Major Junior level like Byfield, Vierling, and Stranges.
The most hyped kid entering the WHL is a defender (Guhle) and same with the USNTDP (Kleven). Although, the only two prospects who have proven themselves as legit so far are Lafreniere and Holz. Justin Barron had a promising year also, but he's a defender. The top kid entering the Q is Hendrix Lapierre, who is currently a center but is on the smaller side and could be moved to the wing.
I agree with you premise about Hughes, but I don't see how 2020 is looking deep on centers. That projection is relying heavily on kids who haven't played above AAA or High School hockey at the NA level. In Europe, the only person I can think of doing well at a U-20 level is Holz. No one else played high-level juniors in either Finland or Sweden for more than like 3 games and if they did they didn't put up points.
One funny thing I'd point out. Teams that have drafted 1st in the last 2 years have both made the playoffs the next year. The only team since 2013 to repeat in the top 10 was the Oilers. Avs, Leafs, and Devils all made the Playoffs, while the Panthers drafted 11th the next year. Now, I don't expect the Sabres to make the playoffs this year, but teams have turned around quickly recently. Although, its unclear if any of these turn arounds will be sustained, as the Leafs are the only one of the four to make the playoffs the year after making the playoffs (unclear with the Devils), Avs regressed heavily, and Florida improved but then regressed to missing the playoffs 2 years in a row.