While I have not seen a reference to man returning, the halachos of meat would still not apply even if the man did return. Note also that the man only fell when Bnei Yisrael were camped around the mishkan in the desert. When Mashiach comes, we will be living in all of Eretz Yisrael and not in the immediate vicinity of the Bais Hamikdash.
Rav Hirsch on verse 3 cites Chulin 16b and 17a showing a machlokes between Rav Yishmael and Rabbi Akivah. He says that in the desert the Jews could only eat meat that was brought as a korbon shelamim. It was only after the entry into Eretz Yisrael and the permitting order in Devarim 12:20-21 that they were allowed to eat non-sacrificial meat.
Rabbi Akivah says that it means that only sacrificial meat required shechita and in the desert the status of neveila was removed by simple nechira. After entering the land Shechita was required.
Rambam says that the halacha follows Rabbi Yishmael.
In either case, it appears that even if the man would fall again, the desert halacha would no longer apply. Given that we would still not be living in the immediate vicinity of the Mishkan, Rav Yishmael's view would be unable to apply as we could not bring every animal to the Bais Hamikdash for a korbon shelamim. Thus it would be impossible for the rule to apply if the man fell again. Rabbi Akiva's view would also imply that the rule of the desert would no longer apply as shechitah would still be required for both kodshim and chulin.