Now the reanimator subclass makes me to remember the 1999 sci-fi horror movie "Virus". Could a reanimator to "craft" (almost artificial) muscles for biopunk machines? For example a crossbow that reloads itself.
I wonder how would be a subclass about the dread elementals (blood, grave, mist and pyre), using these to fight against undeads.
* Now I am thinking about "Nova Falkovnia" with the "original" Vlad Drakov. Here the key is technophobia. To stop the undead hordes an army of constructs are created but these are like the gothic horror of Skynet + 1984. If I explained it with other words, it is like the governor of the Walking Dead controlling an army of clockpunk "borgs". But there are also cute autognomes! Or maybe this Vlad Drakov is dead but as ghost he has got the power to posse machines and constructs.
* The church of Avacyn (Innistrad) should appear in Ravenloft.
* I have listened something about the law of copyright to be changed, but if the company enjoys enough brand power and prestige they shouldn't worry too much. Now the first Mickey Mouse cartoon is public domain, but we know it is not so easy other companies dared to use it.
OK, Infestation: Origins (videogame) and "Twisted Childhood Universe" (cinematographic franchise) could be "adapted" or reimaginated for Ravenloft. (Is your a PC a werebeast? Then face to Bambi: Racknarock!)
* The shifters/theriantouched (from Eberron) should reappear in Ravenloft 5e. The "nerferd" medusa from Eberron could be a PC specie.
How would be the dragonborn version of infernal/upper planar dragons? (Howling, hellfire, Styx, pyroclastic, rust, Tarterian, gloom, chole, deathmasks). And abbysal genasi? (Caustic, Cinder, Plague and Void). And the Wisplings(Fiend Folio) may be small but within a right story they could be as dreadful like the crossed (ultragore comic), they would be like the jerren (evil halflings) but with different racial traits.
* Do you remember the survival horror games "Haunting Ground", "Forbidden Siren" or "The Rule of Rose"? They could be source of inspiration for your own games.
* Let's remember the novel "Heir of Strahd" will arrive to the book stores soon.