There's one issue confusing me about this... When they're using stock footage over five years old (I know it's only a small amount of stock footage) isn't it going to look seriously outdated and obvious? Even the series from three years ago look very dated now.
They could however re master or fix it up.
Nah....I don't it's going to be outdated, but I doubt that Adness would adapt Black RX because technically, the tone and the qualities of the footages wouldn't match the aspects of its adaption. Plus that would draw a lot of confusion. That's why Adness decided to go with Ryuuki first because they are trying to catch up with newer stuff or whatever.
But who know, maybe they could re master Black RX, maybe they won't.
I think Adness should adapt Faiz, Blade, Kabuto, and Kiva.
Faiz would definitely a perfect show because it's sort of like a pick up where Agito left off.
Blade, not a bad choice you see there were different methods of using the cards when capturing the Undeads and performing the Hissatsu attack than in Ryuuki
Kabuto is probably the most easiest one to adapt, the only that Adness would do is not focus on the main character quoting his grandmother and make it look seem like it's everyone's show. Also there would be a few changes on the plot line and add a different type of connection between ZECT and the Natives besides turning all humanity into the Natives at the end.
Kiva. I haven't seen much of it, but I say it would have a darker adaption especially making it into a typical vampire hunter type of show.