While it’s always enjoyable for readers to see major book scenes translated almost exactly from page to screen, some divergences are great.
That wouldn’t necessarily be the worst thing in the world.
That’s how Murtagh is still alive!
Of course, John Grey is due to appear in the Outlander narrative more in the future if the show continues to follow the plots of the books; if he does get a spinoff, it would be either somewhat beholden to the parent series or force changes to the parent series’ arc.