Not sure this arrangement is a good idea for Laura and Genie's friendship.
Honestly, this is a non-issue. Friends come and go but tennis careers are over before you know it and if this arrangement benefits Laura it will have been the right decision even if there is some friction between the two. Also I don't agree with this notion that Laura doesn't have the 'killer instinct' and puts things like personal relationships ahead of tennis. Her coaching history as well as firing the agent she's had since age 13 just before the US Open really proves that she is prepared to make tough decisions, where people could end up getting hurt, if she believes it will help her career.
Regarding the set-up, I think it's a good temporary solution, she will be training in Florida and not in London which will keep her focused on training and away from the London party scene.