By the end of the year we'll have.
-Superman
-Arkham
-Batwing
-Green Lantern
-September Attraction.
5 Rides.
I think it is safe to say that the Superhero area will be well and truly built out by then, which makes sense...There's not a lot of space left unless you do something like stick a flat in the middle of the Superman sand area, plus I think they have run out of 'good' super heroes. The next ones in line (Say Flash or Wonderwoman) probably don't warrant an attraction themed to themselves just yet, and if they do, it would be a flat as mentioned above IMO.
At IOA there are 4 rides in Marvel Super Hero Island (Hulk, Spider Man, Dr Dooms Fearfall, Storm Force Acceleratron)
At SFMM there are 4 in DC universe (Green Lantern, Batman, Flash Speed Force, Wonder Womans Lasso of Truth) plus Superman and Riddlers separate to it all.
In conlusion, I wouldn't stress too much Whitsy. I can see where you are coming from, but at the same time it's a catch 22.
-If we want to have themed super hero area, there has to be a choice of attractions in it (4-5) for it to be worth making.
-If we want to have a choice of attractions, it's going to take a little bit of time to actually establish the numbers needed. We're lucky in a way in that from GL to Arkham to the September Ride we've had them all built out in a 10 month period.