The Fire are keen for the 22-year old to further his development in a professional environment such as Old Trafford and goalkeeping coach Aron Hyde says it is still a possibility.
"It's still a work in progress," Hyde said. "(Johnson's) out of the country now so it's hard to set things up."
Chicago are trying to tee up a relationship with United following the friendly between the two clubs in July and head coach Frank Klopas sees it as a great opportunity.
"These are opportunities we create with the relationships we build," Klopas said. "I think we'll be looking to do stuff like this (with other Fire players) in the future."