SiN episodes coming to a store near you...

Ritual Entertainment and Valve are releasing their follow-up episodes to their 1998 shooter SiN to a retail outlet near you. That's all well and good but I'm interested in how well this would work for episodic content like this. Will consumers be more willing to purchase the episodes from a retail outlet or would it eventually end up costing Ritual and Valve more than what it's worth? It was initially thought that these episodes would be released thru Vavle's Steam content delivery system but apparently they weren't too confident in only that one channel for distribution. I think it makes sense being that this is the first of many episodes to come but for future episodes, I think it would make more sense for Ritual and Valve to use Vavle's Steam but eh, what do i know.