I thought he was dead too. Then I watched it again. So then I wasn’t sure. From what the producers said, he’s going to be back, but greatly changed.
That could be as a walker. Or as no more mister nice guy or something else - unknown at this point.
Bitten people come back as walkers.
Eaten people come back as zombie crap.
Not enough left to come back as a walker.
Glenn could have serious PTSD for a time.