1. $25M is conjured out of thin air. There's no evidence that's what the actual price will be.
2. Speculative for sure, but I think a lot of people expect it to grow by a LOT more than $10M per year once the new TV network deals come through. 2021's cap could be an issue, because the league is facing losing Billions from losing fan attendance, but its also likely to be a record-setting year for TV audiences, which means TV networks will be willing to pay significantly more for TV network rights. And that's before the NFL starts getting more lucrative paydays from streaming services, which is already happening and will already continue to grow.
All that points to the fact that $20-25M deals won't be considered that big 3-5 years from now. WRs will be getting that money, LT's will be getting that money, pass rushers will be getting that money, and QBs obviously have for a long time now. You'll see interior lineman breaking $20M in the next 3-5 years.
3. If I were actually concerned that I couldn't get Ronnie for less than $25M next year, then I'd franchise tag him for two years. Even for rising Olineman costs, they'll be less than $20M annually for the next two years. By that time, you're talking 2023, in which case I'd wager the NFL's salary cap will be closer to $250M than it is $200M, meaning $25M a year isn't that prohibitive anymore.