If it’s to explore the Borg homeworld and the tens of trillions of dead drones and processing what Admiral Janeway actually did in “Endgame”, that’s okay.
If it’s to expore the origins of the Borg Queen and why the Borg went from assimilating technology and having babies to assimilating people to repoduce, and that there’s been some longstanding internal struggle between the Queen and the Collective, that’s okay. Maybe explore the idea of the Romulans creating the Borg too, while we're at it.
If it’s to explore the Jurati Collective (should really be called the Jurati Cooperative), Seven of Nine and her “collective” on the Ent-G, the Xbs post-PIC, and Coppelius as a shore leave planet for Xbs (and other synthetic life), and even a possible resurrection on Unimatrix Zero that’s okay.
If Hugh and Icheb are resurrected and made to be Travelers with Wesley Crusher, I’m fine with that too.
Even as a faction in the Temporal Wars, exploration of the Borg is okay. Though they do not seem to be around post-Burn.
IDC about the Borg as a threat anymore. The only place they could be a threat is the Kelvinverse, or something Temporal Wars related.