We've all heard the tales of projects the likes of EOS, Cardano, Tron, etc. being referred to as the dreaded "Ethereum Killers". Supposedly, the marketing teams and shills of these projects make the claim that their product is superior in every way. Not only is this a lie, it is just downright foolish when you actually start thinking logistics.
Trade-offs
DLT is a very inefficient technology. To claim that a DLT is efficient, decentralized, censorship resistant, fast, and cheap is just outright delusion. Each project has to pick and choose what attributes they want to prioritize. Once the priorities have been chosen and coded in, there is very often no way to turn back.
It is this diversity that makes DLT great. Each community has their own niche with their own advantages and disadvantages. Every project is a platform that could potentially be the best host of a particular dapp or function.
Overhead cost
Even if an 'Ethereum Killer' was better than ETH in every way it still wouldn't sap away the development community that has sunk thousands of hours into learning Solidity programming. Because let's be honest, these aren't products; these aren't currencies. These are communities. If the Denver Broncos win the Super Bowl 10 years in a row everyone isn't going to become a Broncos fan, and it's downright foolish to think that would be the case.
This is the same reason why there can be no Steem killer. How many programmers here have spent hundreds of hours trying to figure all this stuff out? They are suddenly going to jump ship and spend hundreds more hours learning the ins and outs of another project because it might be slightly better? No.
Conclusion
Don't believe the hype. There is no one community to rule them all, and if their was, we should be glad that something so incredibly genius was invented to unite the entire world in harmony. Which is exactly why something like that would never ever happen. We'd be hard pressed to even get 10 people in a room to agree on a controversial topic. Why would blockchain be any different?