Why would the parameters of his extension change because he was traded? I'm asking honestly.
The parameters wouldn't change...
"The injury guarantee would only kick in if a player was unable to play the following season after getting hurt. The option year becomes fully guaranteed on the first day of the league year in the fifth contract year (approximately March 8, 2016 for the 2012 draft class)..."
http://www.cbssports.com/nfl/eye-on...fifth-year-options-for-2012-first-round-picks
Since the Commanders already picked up the option, if he is on a roster under his current contract on march 8th, 2016 the option becomes fully guaranteed. Meaning if a team trades for him they take on the parameters of the deal with an active option year (along with its injury and start of season roster guarantees). So any team that has him must release him prior to the start of the year or they owe him a guaranteed 16 million.
The only way around that would be for RG3 to rework the deal, but he has no reason to do so.
So again I ask, why would a team trade for him knowing they would (1) not play him for risk of guaranteeing the 16 million the following year, or (2) have to release him anyway avoid guaranteeing 16 million on the first day of the 2016 league year?
Short answer, they won't. You are either going to have to cut him or ride they year with him.