I'm hoping the show lasts long enough for glasnost, perestroika, Gorbachev and even the fall of the Soviet Union. The reactions of Philip and Elizabeth, as well as their kids, could be interesting.
Ultimately the kids could play a major part in whether they defect.
Already, the show mentioned Andropov, someday becoming General Secretary, because in the early '80s, he was probably big in the KGB. Of course, glasnost and Gorabachev quickly follows Andropov's ascent to becoming leader and his short reign as General Secretary.