As I expressed this on the Future of DC thread...I mentioned that maybe the best plausible action may be to do a Mummy-Esque attraction..and the more I thought about it; it made a lot of sense. So much that I decided to screw around and make an outline of what the Mummy-Esque attraction would include in-terms of that it's area would be the answer to a themed Forbidden Forest area.
Outlining (because y'know, it's fun):
Light Grey: Reworked Backstage
Magenta: New Path for the Forbidden Forest
Pink: a peaceful lake
Green: The forest (maybe include some tributes to Dueling Dragons and Dragons Challenge in a way that guests can't see immediately)
Light Blue: Replica of the Shrieking Shack
Red: Building Extensions for the Mummy-Esque E Ticket attraction
The new area would have three entrances, all within the area of Hogsmeade Village (one next to the Station, one within the Village and one just as you are leaving the Village). You would also tear down some of the second floor walls surrounding the Hogwarts Express, making it albeit a bit more accurate to the film material in some way; as the forest envelops a little section next to Hogwarts Express's Hogsmeade Station.
And of-course, you would have the Forbidden Forest E-Ticket as it would be a large mountainous façade as it focuses more on some of the darker aspects of both JKR and WB's takes on the Wizarding World itself (including DeathEaters, Voldemort and the creatures within the forest itself).
Just my own take on what they should do. Will I be wrong? Probably. But I think this would be the best thing that Universal could do for replacing DC in my opinion.