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.
It is currently happening actually. have you tried betting on directbet.eu? you can see that you can bet which ever coin you have such as dash, eth, ltc and of course btc.
Like the rest of us here i once tried Yobit Dice and you can even use coins that isn't every by the rest. Yobit dice allows you to bet all coins they have listed on their exchange. So yes these alcoins are staying for good and they will eventually be used widely.
Isnt this going to make chaos if there are a lot of online currency out there? I see its good specially for gambling websites and traders but how about the future.