You forgot Shane Black, one of the few MCU film Directors that actualy tried to go out of the trend with some stuff and delivered what i still consider the most entertaining MCU film yet.
There was actualy a thin line separating Mummy 1999 from Van Helsing, VH didn't have the best designs or execution, but the look itself was just about right, with the mysterious looking Transylvania and all. They should just try offering one-shot stand alone films, you can argue that the MCU films were a bit too searialized, unlike what Gunn is implying, even Guardians wasn't sompletely stand-alone, having left a lot of loose plot points to be later resolved (Thanos and Quill's father).
While this type of serialized cinema making is kinda working for Marvel, i don't want every film blockbuster around to be like that too, i mean, you have tv for those long running stories. Star Wars and Avatar are films that do come to mind when it comes to one-shot stories that were able to spawn more afterwards (Avatar still technically hasn't gotten its sequels yet, but they're a probability and Cameron seems to have a lot of ideas), Episode IV does seem like a single part of a bigger picture now, but when you look at it in the prespective of the 70s, it was very conclsive, i mean, the Empire's biggest weapon was destroyed and the Rebel alliance celebrates, only the following films revealed that this was just a small victory for them. Darth Vader himself was shot by the Millenium Falcon, if i had seen it back then i would probably have come under the impression that he was killed.
Back to topic, i have yet to watch Dracula Untold, this strategy seems like it's going to give some bad films that will most likely become guilty pleasures of mine (like Van Helsing). As for how i think the return of Universal Horror should go like, i think that like Golden Age Pixar, they should try making the best films they can without planning to continue their stories, but imply that it's all set in the same universe.
Here's what i think they should to with each one of their franchises:
-Phantom of the Opera: Go back to the original movie and book, hire somebody talented and passionate to do a thriller for this story. Could even have some tributes to the Silent movie, but should also be its oun beast.
-Frankenstein: Hire Del Toro, that's his passion project, discuss with him all the schedules, if he's only available in 2020, then lock him in that date already, in the meantime you can develop other properties.
-Creature of the Black Lagoon: Victorian era creature, make it interesting.
-The Mummy: I think they should divide this one in two different films, both set in the same universe of course, but completely different stories without any other connection besides being set in this crazy universe and dealing with a resurrected mummy. One Mummy film would be an adventure rollercoaster like the Frasier films, but hopefuly with better writting and Direction, while the other would be a Horror Gothic thriller like many are suggesting, but would get a lower budget.
-The Wolfman: Do another remake of the 1941 classic, take what worked in the last film, and try delivering something smarter.
-Van Helsing: Film dealing with an younger Van Helsing, could deal with anything ranging from Demons to Vampires, would be an interesting way to expand upon the Universal Horror universe from a more active point of view, would also allow to use the character as an action hero, while still not interfering with the Dracula story, since this would technicaly be a prequel to that.
-Dracula: Go back to the original novel and Bella Lugosi's version, spend as many years as you need to get this right.
There are many other Universal Horror film you could probably get a good remake of, and the brand could also include some new and fresh ideas too, like films that aren't remakes or reboots of past material, but are still set in this universe and expand upon it.