All 4 will probably continue to exists for a very long time, and it will be incredibly interesting to see which use cases each of them find. Well, Ethereum has a crazy head-start. It will likely maintain it's lead for a long time because of the network effect and bandwagoning. Dan has a track record of creating new things really fast. Tauchain seems like it's full power will become obvious gradually - like to our grandchildren. Tezos is getting much attention, so let's hope they get something released soon.