At one point, Mike Mearls said there is an idea to make a list of separate class of classes made for muticlassing.

I was wondering if that is possible.

Let's look at the Rogue. What if you halve the sneak attack to 1d6 and push Rogue Scheme and Skill mastery back to level 2. Knack and the first scheme benefit go to level 3.

Then the Half Fighter starts with only one maneuver. Maybe start with a lower expertise die of 1d4.

Then you can have a full Fighter5 with 2d8 CS dice, a full Rogue5 with 6d6, a full Fighter4 and half Rogue1 with 1d8 CS and 1d6 sneak attack, and a half Fighter5 and half Rogue5 with 1d6 CS and 3d6 sneak attack.

Do you think this could work?