Many are going to fail. This is a lot like the dot come bust. The strong will survive and if they actually provide value, real or intrinsic, the washing out of the weak will make the strong even stronger. The key will be what coins are providing actual value and how will that be measured.
It's really hard to tell which ones will survive the purge. Naturally everyone would expect bitcoin and ETH, but if we're being honest neither of them has the best technology. Scalability is a major issue that needs to be solved. I like IOTA and their tangles network solution. Each transaction automatically scales the network so the bottlenecks shouldn't happen.
BTW, for the witness do I add you or blockchain? You have my vote for sure.