Miller staked his claim to a promotion to the Bologna marque's works squad with an impressive 2019 campaign that yielded five podium finishes and eighth in the standings, second-best of the independent team riders.
The Australian ended up just 11 points shy of factory Ducati man Danilo Petrucci, whose form dramatically tailed off in the latter half of the season after he earned a one-year extension to his contract following his Mugello victory.
With Ducati looking to finalises its 2021 line-up before the start of the coronavirus-delayed 2020 season, Guidotti believes that deal between the Italian manufacturer and Miller for next year and beyond is now "close".
“The most logical and normal situation is that Jack will go to the factory team,” Guidotti told the official MotoGP website. “After a difficult first year [in 2018], I think last year he showed a very good potential, he made a big step. He is ready for the factory team.
"Regarding Jack, they’re doing the negotiations and, as far as I know, it’s not done yet. But, of course, from both parties there is the intention to do the deal. I think it’s close."
Guidotti added that Ducati would be conscious of wanting to repay the faith Miller showed in its project when he refused a big-money offer from KTM to replace the departing Johann Zarco last year.
"Last year Jack could have gone when KTM offered him a bunch of money, but he stayed with us with, let’s say, not for little money but much less," he said.
"It means he’s very happy with the technical aspect, he likes the bike and the feeling is good."
Negotiations between Ducati and Miller about a factory ride come at a time when Andrea Dovizioso's future at the squad is unclear.
Dovizioso's manager Simone Battistella recently revealed that his rider has yet to receive a concrete proposal from Ducati amid financial disagreements.
Should Ducati and Dovizioso fail to come to terms, it could allow Petrucci to keep his existing factory seat, although the one-time grand prix winner has also been linked to a World Superbike switch should he end up losing his ride.
KTM boss Pit Beirer dampened speculation of a switch to the Austrian manufacturer for Dovizioso when he stated it was his intention to re-sign all four of its existing riders Pol Espargaro, Brad Binder, Miguel Oliveira and Iker Lecuona for 2021.
Pramac meanwhile is reportedly eyeing KTM Moto2 rider Jorge Martin to step up to the premier class next season in place of Miller, alongside Francesco Bagnaia.