First off, I'd like to point out that being a capable fighter, or being able to fight at all, doesn't equate to not being a DiD just as not being a fighter doesn't automatically make one a DiD. An issue I have with KH is that it doesn't make that distinction very often, but it at least shows that even really capable fighters can get into deep trouble sometimes which they need to be saved from. With that said, all things considering I don't expect Kairi to stop being a DiD all at once or to never get in trouble again.
At this point we're not even entirely sure what constitutes a GoL. All we know about them is that they actively fight to protect the light and function as substitutes for the PoH in making the X-Blade. Taking that into consideration I don't think it matters much in the long run. One way or another Kairi's an ingredient in X-Blade soup and being a GoL doesn't change her status much. It would make her slightly more of a target, but for Xehanort's goals, the GoL and PoH are interchangeable.
The way I look at it though is that the GoL aren't limited to seven, that's just the maximum requirement to recreate the X-Blade. Kairi, among other characters, can be considered GoL, but ultimately not fight or be used to make the X-Blade. Officially, Kairi also doesn't have a Keyblade yet, so there's that.