I think there' room for both Collins and Lopez. There's about 4000 centre minutes available per year, which is about what they combined for last year. If Lopez gets a cut in minutes down to 26 a game, and Zach plays 22, the position is covered in year 1 with Wemby as a four.
In year 2 / 3 of our Lord that might be an issue with a Wemby Sochan frontcourt hopefully emerging) but 2 centre lineups can work when there's shooting at at least one position so that the lane isn't clogged. Not a big issue from my POV, and Lopez is awesome as a drop big / space eater next to a generational rim pressure big man.