Armageddon makes its appearance in the Revelation to John , probably written at the end of the 1st century or a bit later, the writer would perhaps have been aware of the Gospels and Luke that deal with the coming judgement, and maybe wrote his book to explain that the end would be soon, perhaps he was surprised that it had not come by his time !
The other verses that deal with this, like the ones quoted by you, certainly read to me as though they should have occured not long after the writing.
There is certainly no hint in the Bible that millenia would pass before "the end", I think those early christians expected it "soon", but like modern day Apocalyptics they are chasing a Will O' the Wisp dream, the reality is that mankind is making the world a better place, and will overcome any problems that are thrown at them, and will be here on earh for many hundreds of thousands of years to come.
No doubt in that distant, better future, many will look back on this time of superstition and ignorant delusion with the utmost amusement.
By then, the "End TIme" cults, JW's among them, will be long forgotten.