I think Snake only had like a year left to live by the end of MGS4.
FUUUUUUUUUUUUUUUUUUUUUCK I COMPLETELY FORGOT. /SOBS INTO A CORNER

At least he'll have one year of peace. ;;;; I just realized though, in MGS1, his "true" ending he ended up leaving with Meryl and now in MGS4, he leaves with Otacon (and their more or less child Sunny). BAAAW.

At least as fine as a cyborg ex-child soldier can be. ;;;;;;;;;;;;;;;;;;;;
PART OF ME HOPES HE GETS HIS BLOOD BACK AND GETS TO LIVE HAPPILY EVER AFTER. I haven't played or read any spoilers on Revengeance SO I DON'T KNOw.