OK, Josh...let's explore that one a bit.
Now that there are qualifiers, you could be right. The qualifiers themselves will weed out a lot of the people that would make "shorter" metcons turn into long ones, and they will also tend to keep those with major form snafus out of the games in the first place.
With a higher quality of entrant, longer metcons would be possible. I would still guess that a planned "long" workout would be limited to a singlet, maybe doublet type. I don't think "Linda" will be showing up anytime soon in the Games, for example. The easiest long workout, considering the Games location, would likely include more running than they have been doing previously and/or rowing.
I think you're right about 5-15 minute metcons keeping folks prepared well for aerobic-type workouts.
Derek, if one wanted to do a Games prep day, I'd highly suggest doing it at least one month, preferably two, before the actual comp., with a big download week (and extra nutrition) following--maybe even 3-4 days completely off, even more if necessary to recover.