So, a lot of people have been wondering if Universal needs another water park or if there's the demand for one. Last year, Wet and Wild attracted 1,259,000 people. With Cabana Bay now open, and with Royal Pacific receiving an approximately 1000 room expansion/sister resort next door, the new water park would have about 2,800 rooms within walking distance, which comes out to a maximum of about 3,416,000 people* within walking distance over the year.
Clearly, Uni would have a lot of need for a water park to draw their guests in.
*I got this by finding the maximum if each room was booked solid with the max amount of people per room for the entire year, then assumed a 72% occupancy level. In that case, I multiplied the max by .72 to find the above number. I honestly have no idea what Uni's capacity numbers are, so I may be low/highballing it. Still, even if it was halved, you'd still have 1,700,000 people per year right next door.