There is almost zero chance that come 2025 Delta will allow you to purchase a Sky Club membership for $695. The question is: will Delta allow you to purchase a Sky Club membership at all?
If they are trying to drive spending on the Reserve/Amex Platinum and deal with Sky Club crowding; cutting membership altogether makes sense; or at least significantly raising the price.

Just run various back of the envelope calculations on what 30, 40, 50, 60, and 70 % cuts of the interchange on the Reserve looks like for Delta and you will understand.