I already posted what I researched about Achilles injuries for Pro athletes and it is pretty sobering.
Bottom line is he will NEVER be what he was before this. And at CB, you better be at peak athletic performance or you've got a big problem.
The Rams can cut him and save good money with a relatively small dead cap issue ($500K) for 2018. It wouldn't make sense to hang on to him and pay him to see how far he can return to his former self. They will move on from Webster.
And BTW, imagine what Seattle is thinking about now with Sherman's Achilles rupture. That's the end of the Pro Bowl version of Sherman and they are on the hook for $2.2 mil in dead cap (not too awful) when they cut him.......which to me is a foregone conclusion.