Well NerdApproved doesn't seem not credible on something such as Batman.
Tangible is money, this movie will make over a billion dollars, domestically most likely. Internationally many suspect it will gross another billion. Total around 2billion, although I believe the shootings may pull it back some. The movie after advertising and production came to about 300million that is a return on investment you do not get anywhere, let alone in hollywood where breaking even in the short-run is seen as a win since you turn a profit with tv rights, dvds etc; in the long-run. Even with the shootings it brought in 170m domestically opening weekend.
Bales agents have probably told him to be hesitant but show a willingness to produce a movie so he gets leverage in negotiations. He got $10m per movie in the trilogy plus I believe 5% of profits? (I may have that figure wrong, it might be less as I know he pulled in an extra 32million extra from bonuses on The Dark Knight). I am sure he would love to increase those numbers in future productions.
The thing about hollywood is they never leave money on the table, I mean the only time I can think of where a sequel would've made big bucks and it didn't happen was with Titanic but a sequel to Titanic would've been pretty much impossible.