If Rambo 6 ever happens, it should utilize a scrapped ending from the original First Blood. The 1982 film is based on a novel of the same name written ten years earlier and spent a decade in development hell before ever making it to the screen, with many other actors almost cast as Rambo before Sylvester Stallone. The movie also went through a variety of different ending ideas along the way, and while the final version works well for First Blood, one alternate ending would actually be perfect for Rambo 6 instead.
Of course, there's no guarantee that Rambo 6 will happen, especially with 2019's Rambo: Last Blood billed as the final installment in the Green Beret's journey, and the fact that it garnered a decidedly lukewarm reception from audiences, critics, and even the book's author, David Morrell. However, Stallone does have ideas for where a truly final Rambo film would take the character. Along with the possible interest Quentin Tarantino has in doing a First Blood remake with Adam Driver, there's at least a chance that the Rambo franchise will continue in some way in the future.
If something like Rambo 6 ever sees the light of day, it will finally be time to utilize the ending that Morrell's novel and early drafts of the original First Blood movie give to their tragic protagonist. The book ends with Rambo's death, specifically at the hand of Trautman, who puts him down with a shot to the head. While this exact death likely wouldn't be quite right for Rambo 6 given its sudden brutality and the fact that Trautman would be long dead by now, it is probably time to say goodbye to Stallone's Rambo for good if there's ever another movie about him.
Stallone's Rambo 6 story concept already has a poetic, reflective tone to it, as it would see the character retreat to a reservation to connect with his Indigenous ancestry and try to find peace. This alone could probably offer adequate closure, but it wouldn't be a Rambo movie without some combat, and Stallone's battered protagonist finally falling in battle would make for an appropriately emotional and definitive ending, as well as pay homage to the franchise's literary roots. As for a potential Tarantino remake of the first film, it's possible that an ending in which Rambo dies could work better today than it would have in 1982. While it's certainly gut-wrenching and unjust, that's a key part of the picture Morrell's Vietnam War novel sets out to paint. Additionally, having a different ending from 1982's First Blood would help set Tarantino's remake apart.
Whether or not Rambo 6 or a First Blood remake happens, a Rambo death ending seems like an appropriate route to take. The Green Beret has been through a lot, and going out either quietly or in a blaze of glory would be a fitting end to his long journey. It's been 40 years since the original First Blood, and Rambo 6 could finally utilize its discarded ending.