Quote from Mecha-HewittWord of Advice: Hiring people is for doing things that have already been established. Can't draw art? Put a placeholder to represent assets in your code. Can't animate (well)? Make something in reference to what will actually be the demo. And if you really can't animate then learn to do some basic anims man! Can't make music? Then goto a resource site and rip something free for the moment. Your first goal should be to create an Alpha. Not a demo. A demo is the polished bi-product of what your team makes. You're in the process of finding people who can make this a reality.
Make a detailed GDD in which you list everything you want to happen: control, assets, requirements, what platform, what language, intentions, inspirations, anything. Give the people you hire to actually work on something. Don't just hire people and then tell them what to do from scratch. If you really want to make this a reality, then you're going to have to establish a backbone. And this GDD will be like the blueprints to your project.
You sir, should be a CEO of some really major company. I see greatness in you.