They've been installing large fountains, and other water elements on top of the platform this week (It looks very similar to how World of Color is set up in California Adventure).
The park area by the water is being made into a multi-tiered viewing area.
Based on rumors it'll likely have fireworks, fountains, lasers, fancy lighting, water screens, projection mapping, zip-lines, and flying drones involved.
Still no details on what the show will actually be other than some of the elements used, it'll dwarf the previous shows based on what's there now. I think the show originally was supposed to happen next year, but when Hurricane Irma damaged the old show's equipment they pushed up the timeline for the new show rather than fix the old one.