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.
People are now actually doing this if you look at Yobit and other exchanges people are more than willing to trade their bitcoin to other altcoin because they believe that one of these altcoins can and will rise to be one of the top crypto currency and be accepted by merchants