Another thing to consider about Muay Thai is that alot of the action within the MMA realm occurs within a clinch. Considering that most styles of striking will restart once the opponents get tied up, MT carries itself further in its application by addressing (even encouraging) clinch fighting. Amongst all strikes in an 8-point offense, elbows and knees are the most damaging, high percentage stopping tools available.
About the only other Striking style that may transition well into MMA that I could think of is San Shou. You can see examples of it here
, and here
. San Shou follows a more traditional style of the 4-point offense (I haven't seen knees or elbows thrown in any San Shou matches), but also allows takedowns and throws. Building off of that, one only has to urgently work on their ground game to complete their MMA arsenal.
The most dominant guy in San Shou now turned MMA fighter is Cung Le. He fights on the Strike Force cards in San Jose, CA. Here are a few vids on him:
In the second clip you get a peak at his trademark move, the Scissors Leg Sweep. He's KO'd folks by dropping them on the back of there heads with that move.