From what I could gather, Russell Crowe as Jeckyl/Hyde was supposed to be the Nick Fury/Sam Jackson role. IE, bringing them all together. Had it worked out. Hence his appearance in the Mummy flick.
That I got-but bring them together for what purpose? Maybe to fight that god of death mentioned in
The Mummy, but why would the monsters fight something that's probably on their side? Or could it have been a reverse-Avengers type deal with the world finding itself attacked by collection of evil?
Second, the abbot and Costello movies are considered part of the Univeral monster collection-so would the modern equivalent be something like
Key and Peele meet DraculaWell if all humans died, Dracula. Has. No food source so he might fight to protect human existence. The wolfman is still human most of the time so he might oppose the destruction of humanity. The mummy wants to rule humanity as a divine goddess so she might fight the death goddess. As for Frankenstein, well he thinks little girls. Are pretty and has a soft spot for them.