Roglic is better than Bennett, I think.I don't think Roglic will be the new Bennett. He already showed more in GT's than Bennett with the 4th place in the 2018 Tour and 3rd in the 2019 Giro plus he is one of the best if not the best, one week stage racer in the peloton.
However I don't know if he will race the Tour next year, if Jumbo wants to have two riders that are able to win the Tour he should go, if not maybe Giro-Olympics-Vuelta-Worlds could be a better option.
I hope Jumbo sends Roglic, Dumoulin and Bennett/Kruijswijk to the Tour next year.
If you want to beat Ineos you need to bring a big hammer.
Roglic seems like a pretty reasonable guy. I doubt he'd pitch a fit if he had to ride as co-leader or even Option No. 2 for Dumoulin, who I think is as good as any current GT winner, if not better.