Well, currently the reason that very few CO frequent fliers fly more than 50k miles per year was because there was no real reason to do so. I know many people who fly over 150k miles per year, but once they hit the 50k mark, they switch to another airline so they can increase their status in that airlines FF program. That was the primary reason that CO increased their qualification levels. They needed to give their fliers a reason to stick around once they hit Gold. Hence the Platinum track. I think that the amount of Platinums will definitely be more exclusive, but it is not as high a rank as say a DL Platinum Medallion or a UA 1K flier.

Regards,
RChavez