BitMEX founder Arthur Hayes tweeted that ETH futures prices are less than spot prices until January 2023. Presumably because traders were hedging their ETH exposure before the merger. If the marginal pressure is on the seller, then the market maker is long futures and short spot to hedge, which adds downward price pressure to the spot market.
But if the merger is successful, the hedgers will cover their positions, so they are net long ETH, then the pressure is on the buyer at this time, and the market makers are short futures and long spot, and the position before the merger will flip.
It’s a positive feedback loop that, if the September 15 merger goes well, will lead to higher spot prices. If the merger is believed to be successful, then this is a positive structural reason.