Did all of the The Thing aliens die, or did one survive? The only one I can think of is the dog that ran away in the ending and also the guy that was shooting at the dog.
Are there any more Aliens than the dog?
Two aliens, and probably only two, survive—the dog and the split face alien. We know that because both of them appear in the original The Thing from 1982, to which the 2011 film is a prequel.
It appears that you have seen the prequel, but not the original 1982 masterpiece. If you find the Thing alien interesting, you should definitely see the original film, which stands on its own as a landmark of the body horror genre. (See here for some more information about the various media related to The Thing.)