If you have a relatively thin IP lineup, perhaps you don’t need to have the EXACT same promotional and merchandising strategy as when you have a very strong one.
Universal is going to be forced to move away from IPs. Changes in the Hollywood economic landscape and competing (weaker) parks securing big name IPs means that IPs will be both harder to license and less impactful. This should have been the year Universal pivoted to leveraging the other, much more signifiant and unique, strengths of the event. However, the event has become so ossified it seems incapable of making even such minor and necessary changes.
The other solution is for Universal to attempt to produce new and diverse in-house horror IPs to stock the event (Blumhouse isn’t enough), but that’s hard, very risky, and requires intracompany coordination of which I’m not sure they’re capable.