I actually would like to see the Mongolian unique bonus applied to the entire 2nd Age domination victory condition - that is, conquering the home continent will net the domination points for all the civs. It could create an interesting dynamic of conquering the homeland vs. exploring the new world.
Currently, 3 out of 4 victory conditions in the 2nd Age are directly tied to the Distant Lands, which means whoever goes to the new world can potentially get all 4 categories, while Mongolia or Songhai, even with their unique bonuses, will still be left behind in 2 other categories. Simply put, those who decided to never reach the Distant Lands will always be at a disadvantage.