I'm guessing that this expansion has been being planned for some time. I'm betting that Blackfish backlash influenced their timeline, but I bet the real driver was rooted in California politics. You have a park that sits on publicly-owned land in a state where moderates and liberals have a supermajority in the legislature. Not to mention it is a state where it is very easy to get special interest initiatives on the ballot - conservative or liberal. They saw the writing on the wall some time ago, to be highlighted by the most recent legislative proposal to ban whale performances in the state. It won't be the last.
By bringing in an "expert panel", throwing in some names like UC Davis and Scripps Institute (some of the biggest players in all things veterinary), and building a new facility allegedly centered on health and based on science, they are mounting a political defense against future legislative or initiative moves. They want to nip this one in the bud because Shamu is their main intellectual property and the rest of the country tends to eventually follow California's lead.
SeaWorld will perhaps buy some time with this investment, but from a purely business side of things, they need to be developing new IPs. Today's educated twenty-somethings are more environment and health conscious than the previous generation. You see this with explosive growth in brands like Chipotle and Whole Foods and declines at more traditional outlets like McDonalds. Is SeaWorld in danger of immediate collapse because of this? No. And neither is McDonalds. They still have a strong core customer base. But they are not developing enough new customers in that valuable "educated 20-something" bracket that is about to start having babies and disposable income. Both will need to find a way to change with the times. A new habitat is maybe enough to keep SeaWorld off the ballot for a while because it will placate your older on-the-fence crowd and keep the San Diego city council members in office. But it's not going to put this to bed on the broader scale.