Either one of two things is true:
- Oda built up a character over the course of several hundred chapters, showcasing his parallel journey to Luffy's and ultimately even having him 2v1 a yonko, just to have him die offscreen in an ambiguous way.
- Kid is alive.
If Kid is alive, then he has a role: to get revenge on Shanks.
But no, surely Kid must be done. After all, its not like his ship sank off the coast of one of the most important islands in the series or anything.