Which is like saying "as long as it remains warm, it will always be summer". It (at least in the north) just does not work that way. Fall comes, every year. And sit-coms do everything they can do with the character sets they have. BBT has clearly reached that point. Some few sit-coms are so successful that the viewers become attached to the characters and put up with, for a while, a series that has run its course. Friends, All In The Family, M*A*S*H, and, the origin of the phrase, Happy Days. But even this comes to an end eventually.
BBT is clearly out of character based plots. Is there anything original any of them can do? So, like the above mentioned, it will now survive on sentementality.