I was just looking this up on overthecap.com ... I am no expert, but from what I can see they have two options.
They can come to a settlement after June 1st and then his accelerated cap hit for his remaining prorated bonus money can be spread over two years.
So his accelerated bonus money comes to $17.8M in 2020. He also gets a $4M roster bonus when the new league yr starts. So that's $21.8M cap hit in 2020.
So if you spread it over two yrs, his 2020 cap hit is $10.9M per yr. Then again in 2021.
His current cap hit for 2020 is $16.8M. So by doing the post June 1st cap hit, it lowers his cap number by $6M in 2020.
Now they still have $10.9M of dead money in 2020 and also in 2021, but it saves the Rams $6M of additional cap space in 2020 over what they are on the hook for now. Might let them keep a guy like Littleton.
The other option would be if he decided to retire they could take the entire $17.8 hit this year and not have to pay him the $4M roster bonus in March.
So in that case the cap takes an additional $1M hit over his current cap number of $16.8M, but then no hit in 2021.
This obviously causes more pain now, but he would be off the books thereafter.