One might observe that the military forces of the world have a single age old mission: protect the citizenry.
One might also observe the militaries of the world have failed at this single mission now for many decades. Perhaps they simply have been fighting the wrong wars with the wrong attitude. Case in point, arguably the attack on September 11, 2001 was the only sizable foreign attack on the US in the past fifty years; horribly 3,000 US citizens died and the military couldn't prevent it. In the military aftermath, trillions of dollars were spent and tens of thousands of civilian casualties inflicted to counter this threat. Yet, from Iraq to Afghanistan, the only people with smiles on their faces was the industrial war complex as they swim in profits. Sadly, America has been sold that violence is the solution.
In my imagined neartopia, the armed forces will be significantly transformed. Massive navies, air forces, and infantries simply are a thing of the past. Were the nations of the world to unify under a NATO style world force they could enforce the occasional unruliness of undemocratic uprisings and warlord insurgencies. This is no easy task, but if accomplished the dream of deploying appropriate resources to actually protect citizens could be implemented.
Give the hundreds of thousands lost to Covid-19, the first new military branch I'd start is the Bio-Corp. With America's armed forces minimized our country alone would have near unlimited resources to actually addresses Nature's ongoing pathogenic attacks on our citizenry. The Bio-Corps could effectively prepare and mobilize for these outbreaks and contain them, saving millions of lives every year worldwide from would-be virus and bacterial pandemics.
Being that it is the 21st Century, next in line, I'd create a Cyber-Corps. This military branch would actively securing data transactions and intellectual property across the world. Utilizing all the modern technologies including block-chain, a single stable world currency and contract clearing house could be established that would eliminate all corrupt and criminal transactions. In the end a trust in human value exchanges around the world could be tied to actual benefit to the planet, rather than economic hubris.
Finally, an Eco-Corps would be essential. This military branch would battle against the human destruction that has devastated the world climate, eradicated thousands of wildlife species, and generally endangered the health of the planet. Countless lives, human and non-human, would see increased safety and improved life experience were we to deploy a fully funded environmental force.
My scheme is of course a pipe-dream...today. But if tomorrow we were to retire the majority of military infrastructure, we could see real benefit across the world. We are now fighting each other for a short term taste of vestigial superiority, and a false sense of security. Our resources and our time would be much better spent directing efforts toward the real enemies that are killing our planet and our fellow humans along with it.