I was looking at the prestige class for rune magic. Are there plans to expand on such secondary classes.Not right now – prestige class as concept didn't test well with players

— Mike Mearls (@mikemearls) August 26, 2017

I really like prestige classes for 5E as a story-driven alternative to multiclassing. How was the UA feedback?not so good – players generally didn't see them as worth the extra complexity

— Mike Mearls (@mikemearls) September 1, 2017