They could be certifiably extinct, and they would still be an example we could learn from. The Stoics haven't really been much of a thing for a few thousand years, and over the last decade or so a new group of people have been enjoying that philosophy. The notion that faith != practice is a small but valuable contribution that at least branch of the Quakers have left in the world, and whether they continue to exist as a group, that's a valuable thing for all of us.
Also, I'd slightly dispute the "indistinguishable from the evangelical mainstream of wherever they live". There are branches of the Quaker tree that are evangelical, but for the one found in (at least) the mid-Atlantic and Pacific NW, evangelical Christianity is about the last thing I'd compare them to. Protestant mainline, sure.
Also, I'd slightly dispute the "indistinguishable from the evangelical mainstream of wherever they live". There are branches of the Quaker tree that are evangelical, but for the one found in (at least) the mid-Atlantic and Pacific NW, evangelical Christianity is about the last thing I'd compare them to. Protestant mainline, sure.