kj is the most played senti on ascent haven pearl fracture lotus and is sometimes played on split
if u nerf the killjoy ult under b site on fracture by making it breakable with breach aftershock again then cypher will return to the main senti for that map
then a small buff to cypher could possibly help break the no senti meta on split rn and bring him back as the main senti on that map as he was in the past (something like making the cages last longer so he has more lurk potential attacking a site the way viper is used now)
this should bring u to a place where kj is main senti on 4 maps (ascent haven pearl lotus) then cypher on 2 (split fracture)
bind doesnt really have a senti in the current meta but cypher sage and chamber do get some picks so i dont wanna mess with anything for that map
now u buff chamber back to a place where hes playable and he can take over the senti role in certain comps on some maps (not sure exactly what i would buff but prolly his trip range)
this brings u to a place where kj and cypher are more balanced in terms of maps where they are the meta senti, then certain teams use chamber instead on certain maps and the 3 sentis that have filled the main senti role in the past are more balanced in terms of pickrate
sage imo should stay the same as shes more of a flex role pick than a main senti role pick and shes a niche pick on a few maps aswell as having a couple maps where she gets decent amount of picks (split and bind)
this is prolly hard to read and understand but i think it would balance the role
tldr: buff cypher and chamber, make breach able to break kj ult again, keep sage the same