12/2 UPDATE:
The Cubs have tendered 2020 contracts to all unsigned players on their MLB 40-man roster except LHRP Danny Hultzen and INF Addison Russell, and RHP Jharel Cotton has agreed to a $640K 2020 non-guaranteed contract to avoid being non-tendered (see ORIGINAL POST below for the reasons).
So Hultzen and Russell have been removed from the Cubs MLB 40-man roster and both are now unrestricted free-agents, free to sign a major league or minor league contract with any club, including the Cubs.
NOTE: The Cubs MLB Reserve List now stands at 36 (four slots are open).
It's likely that the Cubs have tentatively agreed (in advance) to sign Hultzen to a minor league contract after the Rule 5 Draft (with an NRI to Spring Training and for more money than he would have received if he had remained on the 40 -- as happened with Allen Webster a year ago) - AS LONG AS - Hultzen does not receive an MLB contract offer (which would include a slot on an MLB 40-man roster) for even more money from another club in the interim (which is exactly what happened after the Cubs non-tendered Ronald Torreyes a year ago), or a substantial salary offer from an NPB (Japanese) club (as happened after the Cubs non-tendered Justin Hancock last year).
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11/26 ORIGINAL POST: