Like others said, people are going to want to buy in to make a profit regardless of the assets being called utility tokens. But I think you also gave the answer to my question on this page, that is, with non-fungibles, in the same way collectibles are not securities but can become valuable.
If the land is limited or some is located in a more favorable location to attract people than it will surely grow on value.
It depends on the amount of players, if many 3D worlds will be existing in some years, it also can be, that only a few players live in every world and the price remains stable.