S3 Reduced Redundancy is replaced with S3 Infrequent Access (and another lower tier One-Zone Infrequent Access) so there's still some pricing flexibility available.
Infrequent Access is closer. But wow, one-zone sure is only 20% cheaper than three-zone. And the retrieval cost is significantly more expensive than glacier's bulk price.
Actually, looking closer, is one-zone even storing fewer copies? It's offering the same durability, except in the case of "availability zone destruction". So if they're selling three copies for $10 a TB, then the equivalent price for 64-of-96 would be $5 a TB. Cutting that down with cheaper worse hardware would go a long way to get you toward the $2 goal.
S3 Standard and S3 IA store multiple copies spread across 3 zones. S3 One-Zone IA is stored as multiple copies but all within a single zone. They give you the same technical durability but less availability if that zone goes down, and if it's destroyed then you lose all your data.
