I really like the idea of Carl/Cindy. If destiny precludes Jimmy/Cindy (for example, if Jimmy's arrogance broke Cindy's heart, or if Jimmy died), then Carl/Cindy would be the second most desirable pairing for me. My fondness for Carl/Cindy is only growing, and it might even overtake my fondness for Jimmy/Cindy! For the sake of completeness, my third most desirable pairing would be Myself/Cindy...
(Yes, I know, but please, don't judge...) My forth would be An Original Character I Created/Cindy. Since my original character can be anything I want, there is no fifth choice, or sixth choice, etc. I wouldn't want Cindy to get paired up with anyone else anyway! 
I agree with everything you said Octavius2250. I love J/C and it is the only pairing for me. ESPECIALLY on Jimmy's part. I couldn't see him with anybody else. Ever. I'd hate hate HATE if he liked Libby, ended up with Libby, even when they talk I dislike it.
I'm the type that when Cindy is rude to Jimmy I smirk and find it funny but when he is rude to her I find him to be the biggest jerk in the world, and in those moments I see Carl; so gentle, shy and sweet. He was so sad to let go of that alien baby. He's much nicer than Jimmy so I see him as someone that would be good to Cindy. Does that make sense? Jimmy's a nice guy but he can be such a jerk, Carl's nice 24/7. I think he could treat her good and show her what love is because she seems not to know it, and she could fight for him and protect him. Though... This would be if something were to happen to Jimmy, like death perhaps. I'd never want them to break up, move on or have Jimmy find another girl.
I love Carl and Cindy! (But J/C will always have my heart)