The Big Bang Theory: 10 Theories On How It Will End
4. Penny Is Pregnant (And Happy About It)
You know that question every newly-married couple gets asked if they don't already have children? It's come up a few times in regards to Leonard and Penny, but as of mid-season 12, there have been no baby announcements coming from either.
Penny has always been against having children. It has never been a goal of hers and even though she married Leonard and he definitely wants to have children, the couple haven't progressed through the "should we have kids" conversation into actually going through with having them.
One way the show could bring those characters' stories to a pleasant conclusion would be to announce that they were expecting. That alone wouldn't be enough to warrant the closing out of the characters. The announcement would have to come alongside Penny's delight in the prospect of having children.
Essentially, Penny would have to do a 180 and decide she wasn't only happy to be pregnant, but ecstatic about becoming a mom. It would be a great way for the couple to progress from living in the apartment and moving into the suburbs to start their family life. Granted, that would mirror Monica and Chandler from Friends a bit too much, but you never know with sitcoms.