I remapped all of the keys except I left TAB as the Pipboy key. When I played the game at Quakecon, I had to setup my keys before I could play it (I can't play with default WASD setup), and I did not have a problem with my setup.
However I did notice that the [2] key was hard coded to switching ammo types. I do believe there was an option in the control menu to reassign it, but even after I reassigned it and went into the Pipboy and assigned a weapon to the [2] key, it still stuck to switching ammo types. I hope this is not the case in the final release.
I honestly cant think of a big title where you couldn't change the controls since maybe some of the old low budget xbox games (even then I cant really think of 1), heck even some super Nintendo games had remap ability.
Grand Theft Auto IV originally wouldn't let you remap a mouse button to a foot control, but you could do it for vehicle controls. I returned the game because of this. They eventually patched it, but the right mouse button is still hard coded to hang up the phone, even after the latest patch where you can change those controls to something else. I use RMB to move forward, so I have a hard time playing GTA IV because if the phone rings as I start to walk, it hangs up one whoever is calling me.
Mafia II also doesn't let you assign mouse buttons to movement functions for walking, but it does for driving. It was like this in the demo, which started a long heated discussion about it on their forum. As far as I know it wasn't fixed in the final release, and I'm not sure if it has been patched. I didn't buy the game because I couldn't use the control setup I'm used to. I don't know if it has been fixed because I've lost interest now that NV is so close to release.