Damn this show ... still hope it's a misdirection, but the slo-mo + swelling music and all the previous foreshadowing (Hershel's pocketwatch, and Glenn calling Rick a "dumbass," which he first used when they met in Season 1, Episode 2) makes it seem like it's final.
... but if you notice, a body's guts aren't located in the upper chest area, and Nicholas' guts might have coated Glenn enough to make him not noticeable by the horde ... more importantly, production stills released earlier this year showed the actors filming scenes with new character Paul Monroe (heheh) --and Glenn was clearly shown included with the other characters in the scenes.