delericho
Legend
"Nearing its end" is a usefully vague term.
Plus, they do now have a habit of one Doctor-lite and/or Companion-lite episode each year, and they've just established that River has been in the habit of borrowing and returning the TARDIS at various points. So, if they wanted they could bring her back for one of their Doctor-lite episodes - show him starting some adventure, show her borrowing the TARDIS, and go from there. Indeed, there's no reason they need to confine themselves to the current Doctor when doing that.
Plus, they do now have a habit of one Doctor-lite and/or Companion-lite episode each year, and they've just established that River has been in the habit of borrowing and returning the TARDIS at various points. So, if they wanted they could bring her back for one of their Doctor-lite episodes - show him starting some adventure, show her borrowing the TARDIS, and go from there. Indeed, there's no reason they need to confine themselves to the current Doctor when doing that.