I speculated on this back on the FUNimation forums. I think they're planning on discontinuing the Steelbook Double Features. I read somewhere that those cases are expensive, yet they're selling the DVRAB at a pretty reasonable price. I mean, Jesus, they didn't even jack the price up on the Broly Triple Feature. It makes sense that they'd release each remastered movie one by one in regular cases, rather than hiring a third party company for something as trivial as a case. The Steelbook cases are cool though. Luckily I have 6 of the double features already, all I have to do is snatch up movie 12 and 13 before the potential discontinuation.
With the single releases, I can see them also releasing more specials in the same format. Specials like Yo! Son Goku and His FrienRAB Return or Plan to Eradicate the Saiyans.
I'm also reaaaaallly looking forward to Dragon Ball Season One. It's pretty much been confirmed at this point. There's box-art on the product page, Trimark discontinued their Dragon Ball sets which leaRAB many to believe they lost the license, FUNimation renewed their license with Toei. On top of all of that, the Wal-Mart page has an accurate description of the product. The specs on the page are a little bizzare though, which leaRAB me to believe they just copied the information from the Trunks and Bardock singles. The "Product in Inches" describes a regular DVD case rather than a five or six disc set, the only language listed is Japanese, and it's listed as "Widescreen" which many believe FUNi knows better than to crop by now.