Love it or hate it, the Possession story is now an indelible part of the DAYS legend and identity. Camp and fantasy/sci-fi are intrinsic to its brand, same as the families and yesteryear supercouples/triangles, and you can weave the two cornerstone eras of DAYS together carefully and successfully - it just so rarely does. They're wise to revisit it in theory, but in practice I don't think they have the budget or skill to execute properly. It can't be a one-off, and it shouldn't be another round of ol' Dee being possessed again. Marlena should be the heroine here, the wannabe exorcist. I first came up with the idea of it being Will early in the 2010s when Chandler first started getting a fleshed-out role and Will was acting out, but it could be any number of characters - or multiple characters. And there's all sorts of ways you could play up the horror in a genuinely creepy way. Some of it requires money, other parts just require taste and restraint, which Ron rarely has. Look at films like Hereditary and you have a roadmap for a lot of what you can do scares-wise. But Hereditary has a story/themes not that dissimilar from the issues that beset Marlena during the original story - a woman/mother/wife fraught by trauma and heartache who gives way to dark forces.
I don't have any faith in them to do this well, but it was inevitable it was going to be done someday. It just should be done right. Hell, you could even use this story to finally exonerate ol' Ben (either say the Devil made him do it or preferably that he was framed), but Ron will never do that because he has never accepted that any of the rapists or serial killers he writes as 'edgy' heroes need that - he considered it a personal insult to his ego to be pressed to try.