Alex,
I’ve seen both. Some of the bigger affiliates make new sites specifically targeting live gaming and also having some level of representation on their existing sites. The live gaming niche compliments existing casino sites well. Poker sites do not convert as well as casino sites. Different demographics.
I do believe that the live gaming will be a mainstream one day, and those who start now will see a great return. The keywords and material are unique and getting decent ranking on highly profitable keywords are still possible with little or no budget (other than time).