:3~ have a reputation to uphold.
That's the likely scenario, yes. Riku doesn't really need to Duel Wield for a while. Sora Duel Wielding was fun and all, and had to do more with him being fused with Roxas - an event we knew about, so it was "safe" to let him do it.
Riku Duel Wielded for 30 seconds and even then the event was overshadowed with Kairi using the Keyblade he pulled out. Wonderful attention diverting, Nomura.
If she does end up being able to wield, it might reflect back on why she was even able to hold the Keyblade now. I'll give them that. However, that depends on the circumstances of her ending up wielding and the point in time she became able to wield.
tl;dr no, Kairi holding it now probably means all but nothing save giving Nomura the opportunity to use her as he uses her best -
a red herring.
He did it with Xion's face
he did it to throw everyone off the trail of SoRiku.
He did it again with Riku Duel Wielding.