That is the 'amazing' story!
There are many finer points to this which cannot be covered (due to lack of knowledge) but Jesus (pbuh) was born with miracle like being able to speak from birth. He never lived a 'normal' life like all other prophets before being called to prophethood (although I know almost nothing of his early years). He never married and was purely a servant of Allah. So he will be given the chance to do so.
Hence when he does descend, he will not be the 'leader' of muslims as the final prophet was Muhammad (pbuh) and has his task to only kill Dajjal. He will live as a normal human being and face death like everyone else.
Personally, I view this as another 'miracle' for Islam, aside from the Quran. Like the Jews, they spent thousands of years waiting for their promised land without ever wavering in their belief that they WILL get it back (which they have), we muslims too have our miracle that will come to further 'authenticate' our belief in the coming of Jesus at the end of times.
The question then becomes, (if it happens in our lifetime), what will we do? More like what would I do? Declare him a 'quack' and ignore the sign or join the ranks of the believers? I dua that I will be amongst the believers.