I've heard a radiant and mod tools is very much possible for the game but if they will deliver it will be another story.
Well that is same answer we got with CoD: Black Ops.
And so far only BO Modtools. And then it gets silent.
Those World at War mappers want to move on.
Black Ops wasn't set to be able to have the radiant because certain files were locked in to where the maps couldn't be transferred to the server but MW3 is different and it is very possible. So it's not like the same thing with BO.
BO pcdev always left the door a bit open. And that made it more confusing.
Lets hope MW3 will be as promised. Going back to the full PC CoD package.
Most likely for legal reasons. I'm sure that IW/Sledgehammer WANT to give the PC community what they want, however, you have to remember the cost and complexity of giving us those things.
You post a lot of threads for how new the forums are. Anyway, I wouldn't be surprised if they released it with mod tools or not.