I think the FX president said they will get as long as the show runners want to wrap up the show?
So they're not as under much pressure for ratings and you'd hope they wouldn't resort to overly dramatic show business conventions.
This podcast with the show runners of The Americans and Jack Barsky, who was a real life "illegal" spy for the KGB indicates that the illegals didn't kill. Barsky himself said he never got weapons training, only self-defense, and he never killed:
It would be more historically accurate if Philip and Elizabeth just quit or the spying just petered away. Although Barsky was an illegal after the fall of the Berlin Wall, he basically told his handlers that he had AIDS and they let him walk away, with a nice tidy sum of money to boot.
Of course it's still early but it would be nice if they reached the Glasnost/Perestroika era. Andropov, who was referenced in one episode, was a KGB guy I believe, but he was only in power for a few years. Then it wasn't long before Gorbachev got into power and it was the beginning of the end of the USSR.
More than the action, it would be interesting to see how the characters would respond to these huge historic changes. You'd think Philip would like what Gorbachev did while true believer Elizabeth wouldn't. Of course them arguing about politics back in the homeland may not make for compelling television but if they're not under huge pressure for ratings, maybe it's worth exploring other ideas.
At first the gimmick was the two characters doing disguises and acting out different roles but that hasn't netted them big ratings. Maybe the sweep of these huge historic changes being reflected in the characters can't do any worse.