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.
No, I don't think so. There are already some cases where other cryptocurrencies are accepted as direct payments for products and services, however this use is of minuscule scale compared to Bitcoin. There is also zero indication that acceptance of other cryptos is increasing in any way. And why should it? The other CC's are not offering any meaningful advantage over Bitcoin for that purpose.
Bitcoin had a first mover advantage and as a result enjoys the largest support as a currency. The resulting network effect is very strong and will not be broken easily. Other cryptocurrencies need to offer revolutionary advantages over Bitcoin to be able to compete. I don't see any altcoin that fulfills this criterion.
ya.ya.yo!