I’ve said it before but you could add another 3 or 4 Capcom characters and it wouldn’t even look weird. They have such a treasure trove of great franchises.
Of the existing partners, I'd put Capcom in 3rd as far as my 'untapped potential' list goes. Sega sits far-and-away at the top for me (PS/O, Virtual On, Shining, Jet Set Radio, Space Channel 5, Skies of Arcadia, Nights, Kid Chameleon, Alex Kidd, Panzer Dragoon, House of the Dead, etc.), followed by Square Enix (FF MMOs, Tomb Raider, Chrono, Mana, Legacy of Kain, Star Ocean, Gex, Parasite Eve*, Deus Ex, etc.).
Capcom does have a lot of fun newcomers, but I doubt they'd ever go far enough down their list to hit the ones I'd actually like to see (Breath of Fire, Dino Crisis, Onimusha, Vampire Savior, etc.) Or just give me Tron Bonne.... That'd be cool too. >_>
You know, for as much as we like to talk about unrepresented genres on the roster, we don't tend to talk as much about Adventure games as a genre. Visual novels aside, of course, as Phoenix Wright tends to be talked about a lot.
Even though they're technically from different genres, I sort of throw Guybrush Threepwood and Carmen Sandiego in the same bucket, as they both cover older eras of PC gaming as well as genres/demographics that have largely faded. Carmen is my more desired of the two right now, but I'd be down with either of them, and Guybrush might actually have more impact.
*OK... Parasite Eve sits in a weird spot. The series started as a novel, but the games used an original cast with just the general setup stemming from the phenomenon introduced in the novel and a small reference to its events, so I don't know if that would rule it out. Doubt it, but eh... Then again, I don't even know if Square holds the license anymore since they did everything they could to distance themselves from the story beats of the novel in the 3rd game, even dropping "Parasite Eve" as a title. Frankly, the 3rd Game is almost a franchise-killer for me, so if anything has to go that route to reference the series, rather than focusing solely on the first two games, I'd prefer to just drop the issue and move on. >_>