Wait, Wildlife Docs is being canceled? It looks like it's still on track for a new season. If true that's a shame, as it appears to be well-received (8.4/10 on IMBD), and I'm sure it's given the park some exposure with non-Floridians. It also gives BGT something of a brand to build on. SeaWorld has used the SeaWorld Rescue theme with great success, so a "Busch Gardens Rescue" would seem fitting here.
As the topic of this discussion points out, Busch Gardens really needs to invest in more than just roller coasters. The weather alone is a big enough factor to justify at least one indoor ride. But beyond just that, there's also the fact that many people won't or can't ride roller coasters, and for them Busch Gardens has fewer offerings than ever.
There's also the fact that the park's ride lineup is extremely lopsided, with as many as eleven coasters by 2020 and two (or fewer) of every other form of non-kiddie attraction. Their own advertisements ("Corks and Coasters" comes to mind) inadvertently point that out: You'd only be coming here to drink wine or ride roller coasters. Even Cedar Point, the "roller coaster capital", has a more diverse collection of rides. Focusing solely on roller coasters basically limits the potential audience to enthusiasts living in southern and central Florida who don't want to travel outside the state. A lot of people talk about a niche market for it in Florida, but they've already got that market cornered.
Also, with regard to merits like immersion and theme, coasters are just kinda... lame. That's why locals generally think of Busch Gardens as the "boring" and "trashy" theme park of Florida-- those are actual quotes. There's not a whole lot to differentiate Kumba from, say, Blue Hawk at Six Flags Over Georgia, at least in the eyes of the general public; they're (relatively) "cheap" thrills, by theme park standards. Busch Gardens will probably never be able to beat Six Flags and Cedar Fair in the roller coaster one-upsmanship game, and I wouldn't want to see them try.
What they should do is establish themselves as a high-quality theme park that offers a good mix of attractions catering to everyone. I've probably said this before, but SeaWorld Orlando and to some extent BGW are great examples of what the other SWPE parks should try to be. Not Disney/Universal per se, but decidedly classier and "themier" than a regional amusement park.