Well Daryl would see Merle but who would be seeing Noah?
Probably Glenn. He was the one who witnessed Noah being eaten alive by walkers. After he told Glenn to "Not let go" just before the walkers got to him, I think he meant to not let go of everything he's overcomed which is fear. (Remember a few episodes back, he got his first kill against a savior. He was terrified of killing the living but he knew it had to be done.) I could see the producers having a flashback to that exact moment and hearing those exact words from Noah just before he gets whacked by Lucille. In his mind, he would feel guilt for letting everyone down including himself. Most importantly Maggie and his unborn child. What way to end Glenn's story by making him feel like a failure as a husband and father by not being there for his family before his death. That would be extremely tragic to the audience but it would work IMO.