You can see the obvious back door built in place to reverse and redeem Ben down the line. But I feel that Marvel really likes the idea of a twisted, villainous version of Spider-man in play. Especially now there is no more Superior, Venom has long since been redeemed, Doppelganger is dead.
The fact they are using Peter's clone to act as the mirror adds more guilt and responsibility onto Peter.
It all hinges on how Dark Web ends... If there is a moment whereby you see a glimmer of hope that Ben might turn back to the side of the angels, he likely will in future. But if he doesn't? Then we know he will remain a villain for the foreseeable future.