I don't really understand it either. And it can hardly be like anyone doesn't know it's on. I think it's been on at the Novello longer now than any of its previous homes. I think that's one of the smaller West End theatres, isn't it?
It's the 25th anniversary of the musical next year (and the 50th anniversary of the ESC win the same day), so I'm sure everything will be ramping up for maximum hype. I don't know if the show is in any danger, but they absolutely won't want it to close before then and potentially be seen to damage the Abba brand.
Zoe Ball apparently mentioned on her show last week that she was meeting with Bjorn, and people speculated it was about this show, which i think is very likely the case. I doubt he'll feature every week on the show, but can imagine he may for the final, and perhaps with some pre-records before. He's clearly incredibly shrewd.