Hmm. At the end of CT, the evil was extinguished, right? The characters go back to their homes, but the others (3 main people, you know who they are) go off and explore time. Their future is undefined, but has a definate happy ending
Now, contrast to FF7. At the end of that game, the evil was extinguised, or at least they portray it as so. Square doesn't show what happens to the characters after the final event. The only thing similar to that is a shot of Midgar, 500 years later. Apparently they suggest that RedXIII's race is no longer on the endangered species list, and maybe he got it on with a female that has close chromosomic ties with his species..whatever. Except, they don't say anything about the welfare of the rest of the party.
I wouldn't be surprised if the final flash at the end of the cinematic causes the airship to plummet to the ground in a blazing fireball. So then, it shows a shot of Aeris's face, smiling, because she knows that she can meet her friends in the lifestream, now that they're all dead. Everyone could have survived, but RedXIII took ALL of the emergency parachutes and jumped off by himself.
Sure, they COULD do a sequel, like they did CC, and probably do it well. They definately leave the player with a feeling of mystery, so it could work as a CC-style sequel. However, since I feel that Square did a poor job of telling FF7's story, I don't expect them to do another FF7 story all that well. But hey, I can give them a second chance. It's Square!