There's no inherent resolution to a video wall so it could very well be larger resolution. In reality it's not resolution that matters but pixel density and screen size. 4k is actually overhyped. There's multiple studies that show that unless you're ridiculously close to the screen or looking at text you can't tell the difference. What DOES make a huge difference in perceived quality is color, brightness, and contrast. And an LED wall would be so much better than projection on those accounts it wouldn't even compare. It's actually kind of a brilliant idea. Pixelation would have been an issue historically as pixel density on large led screens was terrible (the largest portion of the illuminations globe is only 256*256 pixels - which is almost fewer than a tamagotchi (sp?) ) but that no longer is the case. They can easily be made much higher res now and the differences you'd get in color and contrast would make even standard hd look better than 4k. Even more interesting-Dolby and technicolor have both been working on new color science models precisely for these reasons for a while now. Knowing that the Dolby tech for 3d has now become the gold standard for theme park 3d (star tours, transformers, Harry Potter) one has to wonder. Because that tech is more color based rather than polarization based it might be transferable to an led screen. I'd see that as being the biggest obstacle.
Heck led would even be better for maintenance in many ways cause it's modular. And no lint would ever get on the projection lens.
Sorry -just talking out loud. The idea is a very good one even if not happening.
They can really do seamless video across many displays/projectors now. It's fun watching them set it up too.. 
