About 4 years ago I've mined about 80 new altcoins shortly after they were announced here.

I've gone through the wallets and the statistics of survivability are:
- Only one of them took up nicely (DASH) and is now valuable.
- About 8% of them sort of survived and gained some small value (not much though ...)
- about 40% of them are alive, but their value is dwindling. Probably they will die off sooner or later
- The rest (about 50%) are now dead.

Note that then and now is a bit different (there were no Scrypt ASICs, less miners in general, more traditional PoW coins and less premine/PoS/ICOs), so as the market is a bit saturated, I guess survivability of a coin born today would be probably worse than 4 years ago, unless the coin would now come with some killer feature or some form of mass advertising itself.