I believe it will be stellar lumen XLM.  Stellar is a sleeping giant that will change the crypto world.

To add the desired project to the ecosystem of Republia, it is necessary to submit it within the framework of the ICO Republia Platform and pass the voting stage among users. In general, the project is curious

The price of EOS also have a great growth after it launched. But still i'm not going to say EOS can replace Ethereum for now. It just have potential to stand beside ethereum than another coin. I would prefer ethereum than another for myself.

Ethereum popularity is due to the ERC20 tokens so everyone can create their own tokens using various ICO projects.

Remember that Ethereum itself is improving as well. Maybe popularity won't fade but will be even greater considering the announced improvements on this specific blockchain.

There are a lot of coins that do not have the potential for growth, and there are not so many promising coins, so I think that if the coin is promising, then there will always be a place in the market for it.

and don't forget about EOS too