According to Michaël van de Poppe, altcoins have remained in a consolidation phase since April, showing minimal price movement. He notes that this sideways action is typical and suggests that an upward move in Ethereum (ETH) could serve as the main catalyst for a broader altcoin rally. Traders should monitor ETH price action closely, as a breakout could trigger significant volatility and rapid gains across the altcoin market in the coming months (source: Michaël van de Poppe).