Before anything, no. Flowey isn't getting added back to deltafell, he's only pictured here because this does relate to him.

The deltafell DX mode i promised a long while back isn't forgotten about, its just been very thrown out of focus in favor of normal deltafell. There's been talk in the team about it and what we should do with it, from adding it as an extra to the main game, or making it semi-canon to the story, but I did want to let you know that its still planned (at the moment) to be made. Whether that's after ch1, deltafell entirely, or just after the demo, ill try my best to get it done.

(If it is made however, it'll most likely be short like ut: hard mode)