grossstadtkerl: I am pretty sure that you have more than 200 ranked rounds as a Champion. Or with other words your average is already saturated, right?
So you just need to lower your average to 55.00 or lower, than it should be done.
I strongly doubt both numbers, 200 and 55.0.
C saturation HAS BEEN 200 before, and many Cs report a new phase of fluctuation. My conclusion to this behaviour is that the saturation number has been risen to a higher number. Same for TLs. To me, it means that "200" is out. "500" is just a guess from the well-known Legend number.
/methinks that 55.0 as the average threshold would be too low. In the "lower" tiers, the sequence is 61.0 (to Legend), 60.0 (TL) and 59.0 (C). From that, 58 might be logical but any number below 59.0 is possible.
Furthermore, one Champ in my CC has been promoted to TC with an average well above 55 (but below 58, IICR).