Reading another language such as Greek requires that the reader understand grammatical construction. I don't know Greek but I'd say offhand that because "thousand" modifies "years" it would have to be plural in order to agree in number. There is no "of" in the Greek.
Jim or Vicky?
You are right that there is no of in Greek any more than there is an "a" there are no indefinite articles in Greek at all.
However I did quite of bit of research on this verse checking with a few scholars asking them if in fact the number was plural for the word thousand in this verse. They stated that this is correct and it should be translated thousands.
If you want an abosoulte translation it would be this...
They shall be sacred ones the god and the anointed and be ruling with same for thousands years.
hiereis tou theou kai christou kai basileusousin met autou chilia ete
Chilia is plural for thousands. In fact if you got to scripture4all.org you will see the following below the word chilia in all instances...
If I am correct I believe the p in () indecates that they are in fact saying the word is indeed plural.
Assuming that I am correct (which I know I am in this case) the issue arises that if indeed John had intended this to mean simply a thousand he could have easily put the word for thousand in singluar form. There is some reason that John used the word in plural from and that would be I believe that he was not simply refering to a single thousand years but thousands (of) years.
There are times where John uses the definite article in front of the world Chilia but this would still not elimiate that it was in fact plural. All it would imply is that the reign of the priests would have a limited length.
If this is the case than it would mean that Satan could have been abyssed in the first century and Christ as been ruling for thousands of years which would definitely fit phrases like "I am coming quickly." It would also mean that it is possible that Revelation does indeed have a partial future fulfilment and that being Revelation 21. That the earth could indeed become a paradise at some point in the future. This is something that I have considered and it does seem possible.
In any case whether people believe me or not is up to them and I could understand if they do not. After all if you were to talk to most scholars and consult most lexicons they will define Chilia as singular. Indeed the theologians I talked to were very reluctant to admit that the word was plural and it was only after contacting them several times and them flat out admitting that the only reason that the word is translated that way is because of theological prejudice that I was able to confirm it.
Nevertheless the word is in fact plural and if you do enough digging you will find that out. I invite anyone do to so and come to their own conclusions as to whether or not they wish to believe that it is thousands of years or not.
But if you do please do so yourself. Do not allow anyone here myself included sway you to what you know to be true. Allow our God, Father, and Lord Jesus Christ to be the one to guide you (yes it is in the Bible literally God, Father, and Lord of us Jesus Christ. No definite article there... ga 1:3 erenie theos patros kai kuriou hemon "blessed be god father lord us Iesou krisrtou" there is no the. This is the way Paul starts off all of his letters. The definite article in this and all cases is implied and added by theologians.)
Ultimately it is God through Christ that reveals things to others. It God who makes it grow. I would rather people look this up themselves and thus connect to God alone rather than look to any human, myself included.