Dont know about the other campaigns, but for the GDI there is alternate endings (one twice as long a the other) depending on whether you use the liquid tiberian bomb on the final mission or not. So logically there could be other ending for the Nod and Scrin.
i just finished the nod missions and the ending really was unsatisfying. iam in act 4 for GDI so will see the ending soon, and iam probably going to go berserk about that ending too. I wish westwood didnt sell their company rights to EA. Way to go EA for making a really suspenseful ending that sucks. I guess from what you guys wrote there will be another C&C. Although who the hell can WAIT!!!! FOR IT the game is just so good and you keep wanting more and more....who knows when the sequel will be out could be 2years or so. I cant imagine how many other people feel this same way. Overall the game so far is really guuuuuuuud i love it so much but at the end you just want more. The game lacks good online play though. By that i mean i always get disconnected from it, so thats Gamespys fault? i think so i guess since it says its powered by gamespy. i really wish they would fix it. Now iam jsut going to finish the rest of the game play online if i could once in a while if it ever stops disconnecting me. I was able to jump into two games at most and play otherwise i get kicked off every 10-1min. So my backup plan is to just play renegade online and chill with that game or WoW or CS Source. Man iam just angry with the ending makes me want to cry. Anyways hope you guys reply and express your feelings about the games ending. Cause i just want to talk about it and get everything i want to say off my chest