It seems logical that SJD will depart following this season as he's going to become a rather expensive free agent which will make him difficult to retain. As for Robinson, I'd be hard pressed to believe the Rams are prepared to unload him as losing two DLinemen simultaneously will really affect our depth. While Robinson carries a large dead money CAP hit if he's cut, there still would be some overall savings to the CAP, but as you've mentioned yourself, getting rookies up to speed on the DL takes time, so I'd be pretty surprised if it goes down this way.
You have also called for Whitworth & Havenstein to hit the road next season as one prepares for retirement and the other you just plain dislike. Again, I don't see our OL depth as being able to support both those losses as Corbett, Allen & Noteboom are also facing free agency next year. Should Whitworth retire as expected, I might be more inclined to believe that Havenstein receives a contract extension which significantly lowers his CAP for the next 1 or 2 years, allowing the Rams to re-sign Corbett & Allen to extensions themselves. Havenstein will only be 30 years old in 2022, he should have plenty of good football left in him.
jmo.