Could HGTV recast the show?
I don't want to catch any hate for this, but seeing as it's a successful show, could they hire a new couple to take over? If Tarek & Christina's marriage is falling apart, they could start a new season with a different couple if they don't want to continue working together. I know this show has been based in Los Angeles, so they could find another couple in LA, or even one from a different city.
HGTV has many other flip shows, such as Desert Flip, Vintage Flip, Flipping the Heartland, Five Day Flip, and those haven't been as successful. They could easily give a different couple a chance to continue the legacy that Tarek & Christina started. From a money making perspective, it seems like it would be a waste for HGTV to cancel a successful series.
At the end of the day, are people watching to see the transformation of neglected properties or just to watch Tarek & Christina? I watch it to see the transformation of properties.
Many times on gameshows and talkshows, the hosts are recasted after old ones quit. I don't see why it should be any different for this.