It looks like the Colts are playing it cautiously this week, especially given the four day turnaround (good thing the league's trying to cut down on injuries, eh?); according to a colts.com injury update, Jerraud Powers will join Vontae Davis and Coby Fleener on the sidelines this week.
Brown, Justice, Mathis, and Satele are all questionable for the game, and have yet to practice this week; Avery's also questionable, but he's been practicing regularly. The Colts have established that they can win without these guys, but they all make a big difference. If Brown and Avery take a seat, the Colts will be lining up with a rookie quarterback, running back, tight end, and wide receiver this week; still, isn't that what we're used to, by now?
Now, if they had a bye week, Thursday night game, and then continued, there would be an 11 day rest, and then a 10 day rest; difficult to restrict Thursday night games to the first half of the season only, but it makes more sense in a league trying to restrict injuries. Bill Simmons has a great article from earlier this year on how the league's not following through with their safety-first policies; not about the Colts, but relevant going into Thursday.
Against any other team, I'd be worried ... but this is Jacksonville we're talking about.