Compare the size of the area that the priesthood operated in with the size of the New Jerusalem. Compare the number of Levitical priests per course with an entire kingdom of priests.
So only Levites will be in the New Jerusalem?
You do know the New Jerusalem doesn't have a temple?
(Rev 21:22 KJV) And I saw no temple therein: for the Lord God Almighty and the Lamb are the temple of it.
Even in Solomon's temple and Herod's temple, the priests didn't live in the temple
There were thousands of Levites and priests who served in the temple
(1 Chron 23:2-5) The Levites were numbered from thirty years old and upward, and their number by census of men was 38,000. 4 Of these, 24,000 were to oversee the work of the house of the Lord; and 6,000 were officers and judges, 5 and 4,000 were gatekeepers, and 4,000 were praising the Lord with the instruments which David made for giving praise.
After the cross, Peter tells his audience that they were a royal priesthood. None of these priests lived in, or even worked at the temple. It is highly unlikely that all of Peter's audience were Levites. Only Israelites from the tribe of Levi could work in the temple.
(1 Peter 2:9 KJV) But ye are a chosen generation, a royal priesthood, an holy nation, a peculiar people; that ye should shew forth the praises of him who hath called you out of darkness into his marvellous light;
You're all over the place trying to make John 14:2-3 fit Dispensationalism. You have the Mosaic Law in place, but then you have people besides Levites living in the temple (against the Mosaic Law). You have a New Jerusalem, but New Jerusalem doesn't have a temple, but then you use the rooms of the temple as your proof that "many mansions" refers to the "general sections" of the temple.