“All the Gift-offering shall be twenty five thousand by twenty five thousand. You shall offer the holy Gift-offering foursquare, including what is possessed by the city.”
The whole portion including the priests' most holy portion, the Levites' holy portion, and the city and its suburbs and lands, are now described as making up ‘the Gift-offering (oblation)' which is thus foursquare and holy. The city too has now been upgraded to being to some extent holy, although notice how it is distinguished from the remainder as not quite so potently holy (see also Ezekiel 48:21). The whole has been offered to Yahweh as a gift and offering around His heavenly temple.
It is difficult in all this not to see it as an attempt to portray the equivalent of a ‘heavenly' portion connected to the heavenly sanctuary, including a ‘heavenly' city, and made up of priests, Levites and all the tribes of Israel, all slowly merging into the holiness of the heavenly temple. How else could Ezekiel do it given his limitations of concept? John saw the foursquare city in the Book of Revelation chapter 21 as the final fulfilment of the vision.