William is the Man in Black
The whole William/Lucas storyline takes place 30 years prior.
-We don't know how old the park is- but we do know it reached "critical failure" 30 years ago.
-We know that Delores is "the oldest in the park". Not necessarily the oldest- the park could also be 60 years old- we don't know. But even if she is the 1st ever- the repair man said shes been fixed so many times its like she's new- so she wouldn't have any old, glitchy, tech at all.
-William, exactly like the MiB, picked up the can Delores dropped and tipped his hat to her. Only Teddy also did the same.
-William and Lucas are totally independent from other guests- we don't see them with the lady who is hunting with Teddy in his new storyline, etc. So yes, they could be present day, but there is nothing tying them to that.
-When William is shot, it hurts him and leaves a bruise. When MIB is shot, it does nothing. Improved bullet technology after 30 years?
-Delores, during the closing scene at the ranch on Episode 3 was having flashbacks and we, as the audience, were witnessing both past and present. She got shot, she didn't get shot. She got raped by the MiB, she shot, and killed the bandit.
-We end with her running into Williams arms. But is this from 30 years ago?
Interesting to say the least. Nothing can really disprove it currently that I know of.