It would be stupid to adapt Decade, and they can't go back to Kuuga and Agito.
I hope they just stick to the order the original series went in. It'd be sad if they skipped Faiz and Blade, there's some great stuff to use in there (mainly the former).
However, from what I've heard, it does seem like they'd go straight to Kabuto or possibly Kiva. It could be cool with Kabuto; the designs were solid and the CG effects weren't horrific, but going to the recent stuff cuts down how many series they can then skip (Decade, possibly Den-O) if they're too difficult to adapt.
I've heard some people suggesting they might go with Blade with the card motif, but I don't know... Stuff like Bakugan is popular with kids at the moment, but the Rider cards aren't really good for a game or collecting, just a part of the series.