Jon Locke is Sawyer

They have very similar facial features. Sawyers hair always distracts from this, as it is meant to until the final “OMG yeah” moment when this is finally revealed. Sawyers “hangdown” hair is an intentional distraction and is never tied back when John Locke was in the scene in case viewers got wise to it. I’m thinking they were selected to act in Lost partly based on their old v young similarities. (eyes, mouth shape, jaw)

Sawyer is known as a shady character who often went under assumed names before the crash. John Locke is just another one.

Young Sawyer as he is in 1978 or (whatever year) + 30 years = John Locke in the present day.

Young Sawyer never makes it to the present day (as young Sawyer) but will sacrifice himself to save Kate.