It will live on in a new form

The manga for a new and upcoming show called Triage X was created to replace Highschool of the Dead. Therefore it's said to be very comparable in terms of content and theme.

Almost all the characters are counterparts of the ones in HOTD. Just read this: http://highschool-of-the-dead.wikia.com/wiki/Triage_X

Sayo Hitsugi will be the counterpart for Saeko (my favorite character)

The show premieres April 10th 2015.