Might I suggest making Final Five and Revolutions/Puppet States mutually exclusive?
What ends up happening is that whatever minor leader revolts out of a Civ will invariably fall victim to the Final Five counter and kill them... and three turns later they're back, rendering the Final Five counter useless as no one gets permanently booted anymore.
Also, I'm of the opinion that the Final Five option itself needs some tweaking. If it's meant to cull players from the game until there are only five left, games that start with 17 or more Civs will NEVER cull down to five (barring players getting eliminated through conquest and/or Barbarians).
Final Five will only kill 12 Civs on Quick (first on turn 100, every 33 turns thereafter, the 12th on turn 466/480). I can't speak for the other speeds as I don't have enough patience to play them (60 turns for a Tier 1 tech on Marathon is... challenging), but I suspect it's the same situation scaled for those speeds.
While this would make things very difficult for Clan players (seriously, starting with zero starting techs AND a research penalty is a major handicap), would adjusting the counter to hit more often if there are more Civs in the game? Something on the order of every 13 turns on Quick if you're playing a full compliment of 35 (including Infernal/Mercurian) Civs might be the only way to end with a true Final Five.