Bolden's recently changed his tune:

“SLS will go away," he said. "It could go away during a Biden administration or a next Trump administration… because at some point commercial entities are going to catch up. They are really going to build a heavy lift launch vehicle sort of like SLS that they will be able to fly for a much cheaper price than NASA can do SLS. That’s just the way it works.”

https://arstechnica.com/science/2020/09/former-nasa-administ...