I couldn't call it any way on which Syaoran we're going to end up with. Perhaps they can merge, perhaps one must be destroyed so the other can have the heart. Perhaps clone!Syaoran's friends will appeal to real!Syaoran to let the clone keep his own heart. Any option seems like it could happen, although there would be something intensely creepy if real!Syaoran ended up traveling with them instead. Like being constantly haunted by clone!Syaoran, and not really knowing if they're the same or not. Then again, both surviving would be awkward (would real!Syaoran just be like, "okay, back to my world, see yah!"), and I personally would be quite disturbed if real!Syaoran, after having been stuck in that tube for so long, finally got free only to have to die for the clone he lent his heart to. Then again, maybe that's the kind of angst CLAMP would go for. Merging seems the least angsty option. Yuuko's statement that real!Syaoran has paid with his "relationship" along with "time" and "freedom" suggests to me that the two Syaorans are one in some way (what clone!Syaoran paid, real!Syaoran paid as well).