TwoSix
Unserious gamer
They could get rid of the 1d6 die and just have it as flat 2*level. That would be 40 at level 20, and 38 at level 19, when rogue hits 10d6. 10d6 is 35 average, but closer to 38 when you factor in crits and the fact the rogue has frequent advantage due to various class features.Sneak attack scaling is way harder. It goes from 3.5 to 35. Eyeballing it, you could try and do a +double your level, but that might scale too fast and it tops at 43.5 which is a significant boost.
So it's mathematically doable with a flat whole number per level; it would more depend upon if they prefer the feel of "mounds o' dice".