If he was involved, good. If he was in the dark about the entire thing, it's an honorable move but it's really just a publicity stunt. It doesn't really change the fact that people within his company are misleading their customer and foreign governments. It's very possible Mr. Winterkorn has everything or nothing to do with this.
I don't think is the "the end" for VW ("in the US"), but I expect it will have a significant impact on trust and therefore sales. It sounds like only some diesel models are affected. The affected models are TDI models of the 2009-2015 Jettas, Beetles, Golfs, and Audi A3's, as well as 2014-15 Passat TDI's. Recalling 11 MILLION CARS worldwide is a pretty big deal though (though they may only recall in countries that care about emissions/where the emissions are above the target). 6% of VW's sales are in the US and the majority of their vehicles are gas, so the impact here is not nearly as big as it will be in Europe, if a problem is recognized there as well.