RH might offer an extremely low commission if PFOF is banned as it should but don't think they will be able to offer free commission, not on a sustainable long-term basis. Even if they do, they will charge in some other ways just to keep a "free commission" front, but it would still be cheaper than IB due to its different cost structure. So nothing much would be changed for IB except its old clients who trade stocks and/or options, which should be the majority of the clients would leave to join RH who rewards them with shares of the company.