I still want to sign him to a modest contract.
Thats the thing. Unless the Bears could get something decent for him in a trade, which the chances of were slim before & all but zero now, I would just assume to resign him. If the Bears could get Forte back on a 3 year deal it wouldn't be the worst move they could make. I believe Forte would be productive in a declining role in the first two years at least of a three year deal while splitting the bill with Langford.
Outside of Forte the Bears just do not have a primary HB on the roster. I believe that Langford is no more than a very good #2 HB in the making. For the Bears who need a QB, OLB, CB, DL, SS & OL in the draft, adding a HB to that list by letting Forte walk for nothing at all would be foolish. Even if they did have to offer him a deal a year too long to maintain him that would at least keep around a productive player, while buying them valuable time & a couple of more drafts to right the ship at the HB position in the draft when they are in a better position to do so.
This being said I would love to have either one of Derrick Henry or Devontae Booker from the draft in Chicago