Mats is one of the best goalkeepers in the world without a doubt. He's not at all the problem.
As for Germany, well Manuel Neuer is probably the best goalkeeper of all time, so that's tough luck for Mats, but I suspect after the Euro Mats will become Germany's #1.
If you haven't noticed, MAtS is everything that Germany does not look for in a player.
Why do you think players like Gotze, Schurrle, Draxler, MAtS etc... don't get into the Germany national team once they are no longer classified as youth? Germans are experts at filtering out 'soft' players, they don't want them in the team, and at most will keep them in the squads incase of injury to players like Neuer (which is all MAtS will be for Germany).
I will happily bet you that they will play Neuer until he is 40 before they give MAtS the spot, but by then MAtS will be playing a 34 year old playing in MLS, China, Qatar anyway. Not anywhere near the CL final like Neuer is doing at 34.