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.
You nailed it! I believe even government will release their own cryptocurrency! There are lots of technology that can't be implemented to Bitcoin without hardforking it and the developer is really avoiding this kind of stuff. So pretty much the technology that can't be adopted / integrated to bitcoin will then be the reason why alternate currency will be used i nstead of Bitcoin. So yeah it is multiple crypto currency to be used in the future not just BTC.