You're not that far off... they've already completed a feasibility study of an on-site hotel (which found it to be a very positive proposition), and the hotel is likely to open along with the African Savannah area in the next few years. Once they have an on-property themed hotel (they've specifically said 'Safari Themed' thus far), potentially an indoor waterpark, an expanded Jungle Jack's Landing, Zoombezi Bay, and the huge zoo itself, they'll have a 3-day sellable destination on their hands.
I had heard that too! I for one think the Columbus Zoo is an amazing zoo! It by far is my favorite one out of the many free and paid-admission zoos I've been to. I look forward to a hotel (possibly an indoor waterpark) and an expansion of Jungle Jacks Landing! When I'm in Ohio, I'm sure I'll be staying at the hotel (when/if it opens). I do think that an expansion of Jungle Jack's Landing would be a great idea, I just hope that they would keep the rides bracelets and get rid of the tickets, or maybe even do a separate admission, kind of like they do for Zoombezi Bay (but still gives you access to the zoo).