Is there anything to stop the core devs saying we want unlimited bitcoin and changing the code to allow it. I mean, 21 million isn't much. 
Unlimited or adding up supply of Bitcoin isn't that possible.It do only have fixed 21M supply.If it do happen that there are some alteration with the entire supply then I would believe that bitcoins value would come to worthless.I don't know why stressing too much on things
we aren't possible to happen.