All corporations have a primary responsibility to benefit their shareholders. That they can combine it with a noble cause is an added bonus.
Quite honestly, I don't think they would lose that many clients. The USG has been trampling over the rights of non-US citizens for years. Snowden's leaks showed just how bad that is. The truth is that the vast majority of those people don't care enough to do anything about it.
Even people who do care (and are technologically minded) still have their Gmail, Yahoo and Hotmail email accounts and online file storage. The effort required to change is greater than the threat to their privacy.
That will not change until the loss of their privacy actually has a visible and impactful effect upon those people. I.e. people start being persecuted by the government for their beliefs or actions in private.
Modern western government's are too smart for that though. Those kind of non-subtle sledgehammer tactics don't work in a society where bad publicity can't be controlled. As an example, see the UK government's U-turn on immigration policy after the public's reaction to a photo of a two year old drowned immigrants's child on a Greek beach laying face down in the waves.