I'm almost always wrong regarding my TWD predictions, but here goes:

(1) Glenn survived the dumpster scene, most likely because it was Nicholas who was getting munched on. We'll find out that shortly before he is bitten, either Jesus (a new character) or Enid distracts some of the walkers and he's able to get on top of one of the buildings somehow... likely because someone helps him, either from on top or inside of the building. We'll find this out during the next episode.

(2) The next episode will also show us who was calling for help; we'll find out that the walls have failed and that walkers are pouring in. The group survives but Carl's eye is shot out. Spencer and Jessie's son are killed. Denise is inured by accident but survives.

(3) The finale will be about the group going to The Hilltop Community alongside Jesus, who has promised to help them get the injured treated with his group's medical supplies. On the way back, they encounter some of Negan's men, who are angry about the herd they moved away from Alexandria, as some of the Saviors were killed. A fight ensues and more of Negan's men are killed. The episode ends with Carl being bandaged up and the other's being treated, as a Savior calls from the front gates and introduces himself. It'll be Wade and he'll make them an offer.

The rest of the season will be about the burgeoning relationship between these communities (and others). In the finale, we'll see Rick, Daryl, Carol and Jesus making their way back to the Hilltop to offer support in their predicament with the Saviors. They'll be trapped by the Saviors and Negan will make his debut. "Ennie meenie miny moe" will end up on Daryl and he will get his brains bashed in by Lucille. His death scene will take up a full 15 minutes and it will make the opening scene of last year's run look like a Disney movie.