There's questions of logistics that need to be addressed. Parking and Security seem to be near their breaking point on busy nights, especially with IoA more popular and staying open past 5. Past couple events Universal hasn't been able to feed guests with any sort of efficiency. And there's only so much space for houses and queues. These are not problems an 11th house or a 20-minute-long "megahouse" are going to solve. The fact they've held at 10 houses for so long implies Universal knows this.
(And yes, the only cure is higher prices, but let's see where they end up this year.)
Going since 2001, and other than IPs/overall quality of houses, the event looks the same to me. The biggest changes I've seen are the transition of zones from scares to selfies -- a change forced in real time by the culture -- and the tribute store, which adds a slight amount of capacity. Everything else is just more of what I saw 20 years ago.