As much as i love the sport, i think we have enough competitions as it is. It would very probably be treated as a third rate competition, much like the Capital One Cup, and used to 'blood' new talent in much the same way as the friendlies it would replace.
I can't really see the problem.
It has to be better than meaningless friendlies, in addition to which many of the Euro 2016 qualifiers are going to be next to meaningless with most of Europe seemingly guaranteed a place in the finals :-)