A curious question..but how much is Universal really making on Marvel. Obviously the movies make a great deal of money - but Universal doesn't get that. Merchandise is almost all profit to Disney (so having it in their parks benefits Disney as well). The rides are good, but as some have said, many if not all would be great with a different theme as well. And IF they did have exclusive rights to DC with the rides, and merchandise (in Florida) for DC, then they COULD benefit more from DC in their parks then Marvel. And the idea of "keeping it out of the hands of Disney" isn't completely true. Right now as it is they are both benefiting from the relationship, and some would argue that Universal having it Marvel in their parks is benefiting Disney more.
I am not saying that I believe Universal is going after DC, but I also don't think it is as simple as you think it is. Marvel is making more money for Disney then it is Universal, there is no question about that. And Universal having Marvel in the parks is benefiting Universal's "competitor" as much as it is helping itself. So the question is, would they ever try to really compete with Disney by going with a competitor product (DC) rather than supporting the Marvel (Disney) brand. I don't think so, certainly not in the near future, but maybe one day.