Jimmy Floyd Hasselbaink is keen to become Charlton manager, but he is only one of a hundred applicants for the vacant position: https://londonnewsonline.co.uk/burton-albion-boss-hasselbaink-keen-on-charlton-athletic-boss-job/
He has done a decent job with limited resources at Burton and he is certainly better than some of the external candidates that have been mentioned.
Fans and players continue to declare their enthusiasm for Johnnie Jackson, but this will be a business decision taken by the owner. If it was down to me, I would give Jackson a 18-month contract, but I am not the person paying the bills.
As for a mass exodus of fans if Jacko is not appointed, if I had left every time I was dissatisfied with a managerial appointment, I would have left multiple times. I still haven't got over Dowie who did us real damage (Karel Fraeye was just a joke in bad taste).