I do agree that Byoudouin vs tokugawa will take place. (i'm undecided who will win)
-if tokugawa wins he gets redemption/ revenge
-if tokugawa loses , ryoma will look at byou as a goal to surpass.
as far as ryoma vs ryoga, i dont think it will take place. ryoga just appeared and we dont know much about him,
-if that match takes place ryoga disappears (by losing) , then brothers cant get to know each other
-ryoga will probably play someone and own them, so that the manga readers and his brother can view how good he is.
-ryoga might even play Byoudouin after tokugawa challenges Byoudouin
the rest of the players is a toss up. I"m still waiting on the next match. IMO atobe needed niou to play doubles.(as shown atobe sought niou the night before). Niou is already 1st string (being ranked 1-20).
So if Niou loses he retains 1st string unless he gets challenged..