Probably, though I expect their O-line will perform better in 3 weeks than they have been, o-line tend to get better as the season wears on. The big thing for proving the Colts D though is the receivers, they simply haven't faced any Tory Holt's or Isaac Bruce's yet this year, much less both at once. It's easy to stop an offense when the QB is throwing to generic receiver number 9, gets a little harder up against pro-bowlers.
we will see of course, but the Browns don't have generic receivers nor do the Ravens.
Besides the Colts Defense will only get better because Mike Doss will be back on the field by then.
Having Tory Holt and Issac Bruce is great, but if Mark Bulger is on his arse it won't matter much.