First, thanks everyone for a fascinating debate on a complex set of topics!
I thought I'd see if I can add some context to some of the questions particularly about our own commitment.
I don't have a view that there's an either-or here on how money can be productively deployed. We have committed to contribute at least half of lifetime earnings from venture capital, in our lifetimes. This is similar to the Giving Pledge that Warren Buffett and others have signed (including John Doerr and Mike Moritz from our world). So there's no requirement that money be contributed to nonprofits now as opposed to later. Each of our GPs will make their own personal decisions, with their families, on timing. But this leaves open the opportunity for some of us to give more actively sooner (like for example Pierre Omidyar has done), whereas others might plow all of our earnings back into for-profit ventures now and for the forseeable future and become active donors later (as Warren Buffett himself did).
So don't think of it as money coming out of the for-profit cycle sooner than it would otherwise -- necessarily. (We did announce a collective $1 million cash donation to six area nonprofits today, but that's hopefully a small part of what we will be able to do over the long run.)
In my own case, my wife and I are active donors now, most notably to Stanford Hospital. But not at a proportion that prevents us from being major personal investors in each of our own venture funds, as well as investors in several other funds and various other kinds of businesses.
I also agree with the commenter that it's not like money vanishes when it goes to a nonprofit. Nonprofits spend money just like any other kind of entity, and that money gets recycled right back into the capitalist system.