Yes that's how it's always worked... Concepts are thought out, often to great detail, but may not keep progressing. So the idea is saved. Sometimes because it was an exercise, sometimes because its theoretical planning, sometimes it's projects that were planned to be built but were stopped. Wdi doesn't always wait for a build order before designing attractions.
But that doesn't mean the whole thing is on a shelf waiting to be built and opened. Just that a fully baked concept would have most of the core concepts detailed out, probably the basic engineering at least started, and a solid idea of 'how' and what a budget would look like. Basically enough that if you had to start... You could leap on it and get the rest of the details started on.
But that's how staging works.. And Wdi is keen on not throwing away old work and concepts. They keep them to learn again from or repurpose.
Its very much like people's reaction when someone says 'the military has plans on how to invade Iran!!!'. Of course they do.. That's the job of the planners to work such things out ahead of time.. So when it's needed.. You are ready *now*. It doesn't mean we are ready to invade.
Wdi studies ideas of all sorts. Remember their job now is to sell their services - not just sit back and wait for a vp to say 'hey, I need a ride'