That's only his opinion based on analysis, I don't see it in reality of Bitcoin market right now. The huge difference of eth and btc price is hard to break, if there's a probability of altcoin season for next coming months then we will wait and see. Predictions is hard to foresee, performance of altcoins is still getting more interesting for most holders and with positivity I think everything will follow in perfect timing.
Bitcoin is the top investment coin and no other coin can go higher than this even Ethereum cannot be more successful than Bitcoin. Ethereum is altcoins and is one of most preferable altcoin currently but we cannot assume that the value of Ethereum can ever go higher or become similar with Bitcoin.
Most of the altcoins are getting successful as the time passes and as we are examining Bitcoin increasing worth so every altcoins is also providing a very suitable option for investment and very soon the season of altcoins will start but the accurate timing is not easy to know in advance.