Mine was replaced for a shattered screen and impact damage last week. The original was an A1428 AT&T model, carrier unlocked. The new model is an A1428 with serial ending in FH1G, unlocked.
At this point, it makes little sense for Apple to splinter their manufacturing even further, and to keep making non-AWS A1428s alongside AWS-enabled ones, and then have to track inventories for each type, making sure the people needing AWS get one sub-model and non-AWS users getting the other. Not to mention the frustration a user might feel if they're on AT&T and told that the only stock the store has is reserved for T-Mobile users, or a T-Mobile user is told the only replacements in stock might not enable HSPA or AWS in their area. So, it's easier to just make them all AWS-enabled going forward.
Having said that, it's ALSO becoming easier now for Apple to replace individual components in-store, like bad lock/home buttons or batteries. So unless you have AppleCare+ and your phone is really bad off, there's a good chance that for common, minor issues, you'll ultimately leave with the exact same phone you walked in with, just repaired.