My honest opinion is that only 1% of altcoins will survive and prosper. The rest will just crash and burn and be forgotten. Ethereum is technically an altcoin and it's already popular. The more legitimate a project is, the faster it'll be discovered.
I agree, the majority of the current altcoin is just junk and can not solve any problems. Certainly in the future a large amount of altcoin will disappear, only really good projects will be able to survive.