remember that time when Sam kept seeing Jess everywhere after she died
remember when Dean kept seeing Cas everywhere after he lost him in purgatory
The year is 2068. Sam Winchester is 85 years old. He begins to suffer severe heart problems caused by being old as fuck. Dean gets in his motorized wheelchair and goes to the nearest crossroads at a speed of 3mph and trades his soul for Sam’s life. It is at this point that even the crossroads demons are beginning to worry about the Winchesters’ unhealthy codependency problems.
I would consider the Winchesters dying at 85 a very happy ending.