The Browns have lost five players through free agency this offseason, and some players over the past couple of weeks have said privately that they view playing in Cleveland like going to college: up to four years and they're out.
But Kaepernick is embracing the idea of playing for the Browns, sources say. The Browns and 49ers have had trade conversations.
To date, the Browns have expressed more interest than the Broncos, who have been slow-playing their interest in Kaepernick so far.
Jackson was the Oakland Raiders' coach in 2011 when the 49ers drafted Kaepernick. Jackson has said that he and late Raiders owner Al Davis wanted to trade up in the second round to take Kaepernick that year.
"I think about it all the time, believe me," Jackson told Sports Illustrated in 2013. "No question in my mind we wanted it to happen and no question I thought it could happen. We wanted the kid in the worst way."