Very quick and very dirty, but you can do it now with almost no effort on your part. As many may know, Curse of Strahd did arrive earlier this year for Dungeons & Dragons 5th Edition, which was cool and all that but it was a tight focus on a Strahd reboot/remaster story line, and focused exclusively on the domain of Barovia, leaving us with precious little to go on in terms of 5th edition's take of the broader Domains of Dread.
Thankfully, entrepreneurial sorts have populated DMsguild.com with lots of useful Ravenloft resources, and WotC themselves have made a print edition of the Ravenloft 3.0 Core Rulebook available. So here's what you need to kick off that fully-functioning campaign in the Domains of Dread using 5E rules now:
Ravenloft 3.0 Core Rulebook and Secrets of the Dread Realms
The POD edition of this book is spot-on, and the only way to identify it as a reprint is by the fact that there's a mark in the back from the printer; it is otherwise an excellent print copy. The 3.0 edition rulebook was useful in that it provided a detailed write-up on the Domains of Dread in great detail, but it is less useful in that it omitted DM-only information for the follow-up sourcebook, Secrets of the Dread Realms. That particular tome is (oddly) not yet available on dmsguild.com but you can find it readily on Ebay for a decent price. Problem of course is you'll need to convert the lords of Ravenloft yourself to 5E, so you could also bypass the 3.0 edition and go for Domains of Dread, which is the definitive 2nd edition resource for Ravenloft, and also quite useful. For my money I liked DoD the most, but over the years have grown to like the 3rd edition version a bit more.
Leonaru made this amazing resource, which is a couple hundred pages of Ravenloft monster conversions, complete with text details and all information necessary to run the Ravenloft beasts in 5E. Get it, then turn it in to your own POD private document through Lulu like me so you can have a play copy at the table that looks like a real book. Well worth it.
If you have the above books, you are pretty much set. But if you want more specific 5E conversions and options, the next two are also well worth looking in to:
Ravenloft Archetypes I: Nightmares of Barovia
This is a dmsguild.com resource which includes lots of archetypes, spells, races and monster options for 5E characters tailored for Ravenloft. It's a decent resource, and while the rule of thumb on "user beware" for all 3PP applies, I haven't seen anything in this book that is particularly egregious....when I do get around to running Ravenloft soon I will likely be able to report on it with some playtest feedback, though.
Ravenloft Archetypes II: Core Domains Adventurer's Guide
This book expands beyond the first, looking in to several core domains and providing material derived from and attempting to expand on prior Ravenloft resources. It's useful in this regard, and worth looking at, though you may just prefer to host a game with the 2nd edition or 3rd edition core Ravenloft books mentioned earlier. Main problem with this PDF is it is not really optimized and has a huge (200MB) download size. Anyone using PDFs on their tablets know what a pain this can be to navigate.
....So, if you have the above five books then you basically have everything necessary to run a Ravenloft campaign in 5th edition, and the only work you'll really need to do will be to convert the actual dread lords of the domains themselves, using whichever version you prefer (2nd or 3rd).