A continued uptrend in Ethereum, along with an uptrend in the ETH/BTC chart, indicates a strong likelihood of the altcoin rally continuing, suggesting capital rotation from Bitcoin to altcoins.
"If ETH has been rising in recent weeks and looks like it's going to continue its current uptrend, then there's a high chance that the altcoin rally you're watching will continue. The catch in this case is that you need to check the ETH BTC chart to see that. Now, to quickly bring you up to speed, the ETH BTC chart shows you ETH strength compared to BTC rather than the US dollar. And all you need to know is that the ETH BTC chart should also be in a clear uptrend and should look like the current uptrend will continue, at least in the short term. And this further increases the chances that the altcoin rally you're watching will continue as it suggests capital is slowly rotating out of BTC into altcoins."