I have wondered when reading about the battle at Megido, what will satans army be made up of? Like you, Im assuming he will use all the people in hell and they will be given physical bodies, just like the heavenly glorified bodies of those in Gods army, although Im not sure about this, I do know though, this battle at Megido would be an awesome thing to witness! He could also use the demons too, as he has 1/3 of the angels on his side, but we dont know how many that actually is, maybe its 500 million or more!
I agree somewhat with your last paragraph, but while parents do let their kids be exposed to some degree of danger and temptation, like high school parties without adults, they still try to shelter them as much as possible, (especially in the modern world today).
A good example of this would be a recent local story, one neighborhood called police about a suspicious white van that had been driving around their residential streets, and one young girl said the man tried to get her to get into the van, so now everyone is worried, every cop in the area is out on the look out for this generic white van, however if this happened back in my childhood years, not as much commotion would be made about it, we would be warned about stranger danger, but I doubt as much police involvement would be offered, we would still be allowed to go outside.
What God is doing with Satan today would be like all those neighbors and cops just allowing that white van to continue to drive thru the neighborhood anytime it liked, to be among all the ‘kids’ outside playing, heck, he would even be permitted to tempt or lure the kids as often as he liked!
While a good ‘parent’ knows how much to shelter and how much exposure their kids can handle, NO parent in their right mind would just allow the ‘wolf’ to be in close proximity to their kids or ‘neighborhood’…see what Im saying?
Especially when we consider how much God is said to love and care for our well being, its said we cannot comprehend how much God loves us and desires us to be with him in heaven.