the non crafting tribes max at 4
ixali tribe will max at 7

after all those there will be a unification quest that jumps them all to 8 automatically

vanu vanu is a bit strange though
the story seemed to end at 7
you get the mount and different color minion at 7
the quests didn't reset at 7
but... the rep is still going up

Will know in a few days i guess