The Hamilton-Russell dynamic is certainly going to be interesting. You can't sniff at the fact that George beat Lewis in the standings and won the team's only race of the season. However, Hamilton actually out-performed Russell for most of the season. Dropped a lot of points after a sloppy start but then generally had the better of him for most of the year. By that point, though, the car was miles clear of the midfield and Lewis was only scratching back a few points over George for finishing a place or two above him in the top six.
It's going to be difficult for them if they're in a championship fight with Red Bull, for example. Perez simply won't take points off Max on a regular basis but Lewis and George will. I think Lewis tones down his mistakes and finds more consistency when he has a championship-contending car and therefore something to lose from going all out for a win/podium. He would beat George over the course of the year in these circumstances but not every weekend, and those weekends could cost him a title against Max. Depends what the competitive order looks like though. Mercedes may have improved in the back end of the season and nicked a win, but as things stand, they still have a long, long way to go to catch Red Bull for next year.