Bad Boys for Life is still technically the highest grossing movie of the year domestically, and while there are certainly a number of external factors contributing to that fact, the movie was still quite popular when it came out in January, likely more so than even the filmmakers expected. The return of the franchise was also the best reviewed installment in the series. The way Bad Boys for Life ended, combined with its success spells good things for the future of Will Smith and Martin Lawrence's characters, but that ending, it seems, was almost quite different, and incredibly dark.
In the version of Bad Boys for Life released in theaters, the villainous character of Isabel Aretas (Kate del Castillo) attempts to shoot Will Smith's Mike Lowery when her son (who is also Mike's son, we learn) gets in the way and she shoots him accidentally. Isabel is heartbroken by the event, and she then tries to take another shot at Mike, but then fellow cop Rita Secada (Paola Núñez) arrives and she shoots Isabel, and keeps shooting her until Isabel falls off the ledge to her death in the fire below.
That's a fairly brutal death to be sure, but it's in line with the action that we've seen up to this point in the film. However, it appears one version of the ending, while it ultimately had the same result, was much more grim, as director Adil El Arbi told Digital Spy. In this version, Isabel actually wants to kill herself after accidentally shooting her son, but she doesn't want to go alone. According to the co-director...
When she sees that all is lost, she wants to jump into the fire willingly, and she wants to take Mike Lowrey with her. Because, you know, she thinks the son is dead, so let's all die together. That was a version that was pretty epic and pretty Greek tragedy. It was too much, maybe [but] we'll never know.
The director is a bit vague as to exactly how successful Isabel would have been in her attempt to kill herself and Mike. More than likely Mike would be saved but Isabel would still fall, leading to the same eventual end that we got in the movie.
The directors explain that they had many different ideas for how to end the film and are pretty honest that they weren't entirely sure which way to go. That's born out by the fact that, while the Bad Boys for Life Blu-ray actually does include an alternate ending, it's not this one. It's a third variation, where Isabel still gets shot by Rita, but doesn't fall into the fire and instead bleeds out on the ledge.