I like it. Castlevania Judgment gives the idea some precedence because Cornell's in it and we all know he's not from the canon timeline. GOS could follow that up with a grimoire based on the LOD setting with a fully playable Cornell.
As for dream interactions:
-Alucard reunites with Trevor, Sypha, and Grant; Grant and Hammer bond over hot blonde witches they'll never have
-Cornell proud of grown-up Henry; John to Jonathan Morris likewise, though the latter is still angry with him despite knowing why he did what he did (they get better as the story goes on)
-Soma, Albus, Henry, and Hammer hit the firing range together
-Richter vs. Lord of the Castle Richter
-Christopher thinks he's the lame Belmont, Simon assures him otherwise
-Leon sees just how long the war with Dracula has lasted, wonders if dooming his descendants to fight him forever was really for Sara or for himself
-Nathan has no idea who the Belmonts are and has to be brought up to speed
And if the plot will call for some major spell to be cast, Sypha, Carrie, Charlotte, and Yoko will put their heads together to get it done.