I think its worth pointing out that we only have 3 forwards to fill 80 minutes (possibly more if Dolezaj gets sime time at center). They are all going to play a lot every game and be key members of the team.
That said, Dolezaj will be better defensively than Huges every single game, and Hughes will only be better than Dolezaj offensively in most games. In games like the last one where Hughes is hot from outside and scores 19 points, obviously he will get the bulk of the minutes. But in some games Hughes will be cold, and in other games Dolezaj will be hot. In both those types of games Dolezaj will play a lot more because he also brings more defense to the table.
My guess is they play a similar number of minutes in total this year, but not because they each play 25 minutes per game. Instead they will alternate who plays most based on who has the hot hand and what skills we need to beat our opponent.