i have been thinking how the show will end. i can't see dean as (so sadly) an old man fishing you know? and since the brothers have separated ( as of now) i think i know what MIGHT happen.
so in the finale dean will by himself being fighting something BIG and it mortally wounds him. sam comes in though and kills whatever it is, stopping and saving everything. BUT dean is...dying... yet he realizes that sam is GOOD! they talk and dean tells sam to live his own life and do what makes him happy and then he dies :'(
it shifts to years later and sam is a lawyer, married, and has a kid... named dean. he is happy though and always remembers his brother.
what do you guys think?! i REALLY think it might be something like this! i would be so upset but think about it and please let me know
We do have our 
