This has been discussed ad nauseam
all over the internet, as an example, (including this site) on why the Island is locked in the 90s with no new additions and nothing but refurbs. Basically Marvel/Disney has the right to approval on any reasonable changes to the area including new attractions, and Disney isn't likely to approve new usage as it doesn't benefit them. Same reason why Uni hasn't given up the rights so far. So Uni has been locked into just maintaining what is there.
So basically if they can swap out Marvel for DC so the whole area can be refreshed, that benefits everyone. Now will that do it, who knows, only time will tell.