They’ve already trained consumers that higher speeds cost more. They would need a compelling reason to keep costs the same after increasing speeds.
The cable company now needs to both increase speeds _and_ lower prices to even keep their existing customers. This is a good place to be, as a customer.
If pricing stayed even close to fixed my gigabit internet would cost well over $10,000mo, considering back in the day I was paying SBC for less than a meg for more than I'm paying for a gigabit today. And that's before adjusting for inflation, those 90s dollars are worth way more than 2023 dollars.