All of that will come. You're right about one thing, some alts will crash or even never take value, like the startup of the internet 'bubble' (that was'nt a real one) but the tech behind crypto, so decentralisation by blockchain or hashgraph (possible next gen) can only become the standard imo.
About facebook, it can upgrade to include crypto by many ways, and if it does'nt others socials networks will come up (like steemit), same for youtube, twitter, etc.
Searchengine are free, but some says results are manipulated, a search engine on blockchain will be a google killer if done right, and it will come up for sure, maybe not next year, but one day.
Paying without any possibility to someone know will not be sustainable, problem is money laundering, but you can pay with any coin with a lot of privacy if you use multiple wallets and/or coins, it could be very difficult to trace transactions (atomic swap, that can make transaction interblockchain can be used for that, and can only be traced by people who really really want to know).
About cryptocats I agree, real cats are way more funny and costs less (even if veterinary and pet foods are not cheap, trust me I know :-D )
Paying dentist or other medical doctors can be made with some coins that will be issued by any social care, will be way more easy for them to handle people who tried to fraud them, just let them time to come up.
About video games, they are a lot of coins/blockchains that want to make networks for players, so they do not have to use the official ones, just google 'ICO games'.
We're at the beginning of the curve of the adoption of a new tech, we are early adopters, just wait a few years and take care about the coins you buy and holds, so just use common sense.
