I think that would be so awkward too if they did that and so disappointing. I think it makes a lot more sense to just pretend they don’t exist then to give even the hope of seeing them and not showing them. They are showing flashbacks of Storybrooke with Zelena and Robyn and fake Hook and later with Regina and young Henry. That is bad enough. They are showing Storybrooke, but not showing the characters you really want to see. I just can’t imagine the point of showing present day Storybrooke with an adult Henry and not showing him interact with Emma.
If they end with them driving into town then fine, disappointing, but at least more reasonable then even giving the hope of actually seeing Emma, Snow, and Charming again. I see no point in a cameo at this point with only the finales to film.