I can only speak for the public sector, but the talented people that stay in the public sector eventually have to move up to management positions for only one reason: A bigger salary.
The real problem isn't about too many managers. It's about politics and culture: "I'm THE manager, so people beneath me cannot make more money than me!"
If leaders eliminated that single stupid, corrosive paradigm from their org's culture and people were paid what they're worth based on merit (not title or hierarchies), these pointless middle management jobs would disappear overnight. "You mean I don't have to manage anyone and I get paid what I'm really worth? Wow! F**k those management responsibilities! I'll take door number 2, thank you."
If you're a manager and don't like this because you worked your way up in the current culture and would feel slighted by this change, you need to STFU. You're not BETTER than your subordinates because of your title. You're just managing others because that's your job that you're officially trained to do - manage people. And those people may be just as important, if not more so, to your organization as you are.