I still don't like your idea because:
It's not handy; which colors do we give the ranks?
You don't give examples.
How could you get the rank?
And the chat and tab menu would be chaos.
And I think there is just no need for obtainable ranks, if you want a rank, just buy one!
This is why I don't agree.
You would get the rank doing objectives, like:
-Be the Blockwars player to get more flags.
-Be the Eggwars player to destroy more eggs.
-Be the Skywars player who teleported most times.
You could make it with patterns of colors, like:
1 = one color 2 = another color
-1-2-2-2-2-1
-2-1-1-2-2-1-2-2-1
-2-2-2-1-1-1
Each number would be for each letter.
And add Names that change a bit, like:
-Changing from Bold to normal.
-Changing from Underline to Bold to Normal to Bold to Normal to Underline (Uff XD)
Finally, it's just an idea. We don't even know if they will implement it.
AND these ranks are for the actual games you got the title.