Well I think what makes a crypto casino thrive in the market depends on their service as a whole. This includes the promotions, bonuses, games, payments, etc.
Personally  I think those casinos that copy the design of others very closely has a very high chance of being kicked out off the market suddenly. I mean, if you know that your favorite casino is being copied so much, will you trust that one that is copying it? I'm guessing the answer is no, so that means that they won't be able to get good amount of customers. Unless they change their strategy.