This is what I think: Ethereum will survive and Ripple will die for sure. Why? Because Ripple is centralized. Just my opinion, though 
Actually Ripple and ETH could work fine together. Ripple would be the gateway to the material stuff and a host of different crypto and fiat currencies and Ethereum can be the intelligence what monitoring and controlling the flow of goods and money.
BTW Ripple not going to be dead soon, there are tons of money behind them and money transfer services and some banks are jumping into it. Ripple's centralized nature is a benefit/requirement for such companies.
. Ripple is an IOU system for making different stuff (e.g.: elephant to BTC) easily swappable, while ETH is basically a framework for making contracts and then enforcing and verifying the processing of these contracts. As relaying between different systems is also possible, in the future it could be a framework for glueing together different platforms.