I personally think Kim and Xavier are stale to watch, not that they might feel stale with each other. I'm a big Kim and Xavier fan, but I wouldn't mind seeing some new faces sometimes too.
I haven't heard Kim say that she wants to win the Hopman Cup very badly or anything, but if she's coming back year after year, she must want it on some level. She's No. 1 in Belgium and I think she'll honour that position by playing the team event.
Liz Smylie should pursue Justine too. Why not try and get them both? Now that'd be a coup if she somehow managed to pull it off.