Personally I believe that when your body dies, whatever you think will happen, will happen. This explains why Christians see Jesus, Muslems see Amed (Haha!), and Jewish people see Moses. For me, I believe I'll incarnate on another planet as a being of another race. I also believe that people can stay in spirit as long as they need or wish to.
This actually is a huge possibility. When the body is about to die it releases a ton of DMT, which is why time seems to slow down and you 'see the light'. When smoked as a recreational drug, DMT is known to blast the user into a spiritual dimension where a few minutes can seem like nearly eternity. So during the few minutes when your brain is still active before you're completely dead, you're on a trip that feels like it's lasting sooo much longer. Of course, if your brain is damaged by whatever death you have then you may not get that experience
If you want more info:
http://www.academia.edu/1970764/Role_of_DMT_in_Near_Death_Experience