I just finished watching The Ultimate Warrior Dark Side of the Ring and I have one question. 

I have heard Jake Roberts mention this before, but why does he insist that Vince had planned a 1991 program between he and Warrior which would end with Jake winning the WWF championship?

Warrior had already dropped the title at this point to Slaughter, who then lost it to Hogan. It seems like there was no plan on putting the belt back on Warrior after his less than stellar run as champion.

Yet, Jake says that he was going to go against the Warrior that year in a title program and make more money than he had ever made before in his career. I do recall the two were set to feud before Warrior left the WWF, just not for the championship, obviously.

Was a Jake title run ever in the cards, or is he just confused? 

I think he was just confused and got conned by Vince.  That being said, I'm 100% sure Warrior was getting that belt back at some point if he had stuck around, because they had so much money sunk into him that they pretty much had to try again.  But no, zero chance Jake ever gets the title given his issues.