I dont think bitcoin will kill off all other ALT coins. Imagine 5 or 10 years from now end users are selling their products online and accept multiple forms of payment BTC, ETH, LTE, etc. Why not??? Just look at this chart here.
http://coinmarketcap.com/charts/#btc-percentageThis is the total percentage of the market that Bitcoin dominates. And since the beginning you can see that the peaks are becoming less and less. So this means ALTs are taking up a bigger percentage of the total Crypto market cap.
I think BITCOIN will be a STRONG crypto. It will be the mother of all cryptos, people will buy it to branch into other ALTs if need be.
Yes, i don't think. Other ALT coins will increase for Bitcoin. If Alt coins increase then Bitcoins increase too.