That's still 5 more games spread all over in the schedule along with the Copa and CL. That's assuming he'll get to play all those games if we win yet another treble.
If you want a young GK to develop and gain consistency then you need to give him a chance to do so and playing every week in the league is what enables him to do that. Bravo is more than experienced enough to handle sporadic game time.
Besides, it's not like Bravo has something to stake claim on the Cups either. You're making it sound like ter Stegen will undeservedly take the League. Using the same logic, Bravo will undeservedly take the Cups.
If not this season then next season there have to be a switch of role. Must be. Otherwise we may as well sell him as I don't think he'll love getting games here and there, a long-term option for a short-term option and have to dive into the market again in a few years for another GK, and probably be prepared to pay much more than the 12m we paid for ter Stegen.
Either that or loan him out like Chelsea did with Courtois. Thibaut Courtois would have sure as hell not become the GK he is today had Chelsea chosen to keep him and given him the CL and FA, Carling Cup games.
Neither would De Gea have become what he is today had Ferguson decided to ditch him to the Cups and brought in another GK to play the PL.
Take a look at Oblak last season as an example. Shaky. Not confident at all. Then Moya got injured and he got 11 LL matches on the trot. He grew in confidence and had a couple of great games and will probably be their first choice in the League next season. That's what consistency does to you.
De Gea, Courtois, Oblak all in the same age group as ter Stegen.
Look at the massive difference in minutes played between Bravo and ter Stegen.
ter Stegen with Copa del Rey and Champions League - 1890 minutes
Bravo - 37 La Liga games - 3330 minutes
You cannot simply compare two GKs when one plays a lot more than the other and the one who plays less also don't do that consistently, but has a sporadic game time schedule.
Stats:
http://estaticos.sport.es/resources...s-enrique-temporada-2014-15-1433847020088.jpg