Rabbeinu Bachaya says that a literal reading is only how the “hamon” understand it, but he holds it is not meant literally at all. Instead, it is a metaphor for son’ei Yisroel (like Eisav, "yecharse'menu chazir mi'ya'ar) who will become our friends. Others who understand it allegorically are the Baal Haturim here, the Ritvoh in Kiddushin 49a, and the Recanti. According to Rabbeinu Bachaya, the rest of the meforshim are just from the hamon.
The Satmerer Rov, in his Vayoel Moshe here, brings the Ramban in Bechukosai (Vayikro 26:6) that says that before the sin of Odom, animals were more refined and there were no carnivores, and when Mashiach comes, they will revert to their original perfected state. Thus, we can say that their physical appearance will change– herbivores don’t need sharp claws or canine teeth. The Satmerer applies this to the idea of their becoming kosher– that they will become kosher because they will develop simanei kashrus. This seems to imply that if biologists would develop a pig that chewed its cud, or a camel with split hooves, they would be kasher. The problem is that besides the halacha of simanei kashrus, there is also a rule that “hayotzei min hatamei, tamei,” that an animal that is generated from a non-kosher animal is also non-kosher, irrespective of its signs of kashrus– that kashrus is not only intrinsic, it is inherent. However, he brings the Ohr Hachaim in 11:7 here that says that the phrase “v’hu geiroh lo igor” is a tnai: their issur is only as long as they have the one but not both simonim, but if they develop the second simon kashrus they will be kosher. According to this, while indeed a pig that chews its cud would be kosher, a camel with split hooves would not be kosher. The Chasam Sofer in the end of Re’ei also uses this derech to explain the Tanchuma.
Note that this Tanchuma is not the only occasion that Chazal allude to Chazerim being muttar: See the Gemora in Chulin 17 on the passuk in Parshas Vo’eschanan, Dvorim 6:11, Batim m’lei’im kol tuv, which says that during the first fourteen years of Yehoshua’s occupation of Israel, everything they found that had belonged to the Kena’anim was kosher, afilu kadli d’chaziri, even ham. But remember that Reb Meir Simcha there in his Meshech Chochma says that although it was muttar to eat whatever they found, those who did eat ham will suffer ‘timtum haleiv,” spiritual necrosis. He thus applies to Katli D’chaziri the concept found by Y’fas To’ar, a hetter that applies only in wartime, and which, despite the hetter, carries grave spiritual risk. So although the two Chazals, the Tanchuma about the times of Mashiach, and the Gemara in Chulin, are superficially similar, according to Reb Meir Simcha there is a clear distinction; even he would not say that the Tanchuma means that the hetter of chazeirim l’asid lavo carries any spiritual risk.
This discussion is also relevant to the gnostic and antinomian ideologies that tend to be associated with messianic movements. Some have interpreted the Chazal about the three epochs: two thousand years of tohu vavohu; two thousand years of Torah, beginning with Matan Torah; two thousand years of the Yemos Hamoshiach, which will be finally followed by 'that world which is wholly Shabbos, as indicating that the need for a life of Torah is only necessary when there is a need to balance some countervailing force. Once the yemos hamoshiach have commenced, there would be no such need. In fact, these movements sometimes drew strength from the tantalizing possibility of fealty to Hashem through antinomian synthesis of kedusha and tumah, as Rav Yakov Emden pointed out when he attacked their use of certain parts of the Zohar. The idea that there is a relationship between the kochos hakedusha and the kochos hatumah, as implied by the stories of the relationship between the moshiach and the daughters of Lot, Yehuda and Tomor, Dovid and Bas Sheva, Shlomo and Na’ama, can be understood as indicating: a) a dynamic tension moving toward resolution, or; b) as paired forces moving toward synthesis, or; c) as equally excessive and inherently unstable results of the inability to maintain a middle path.
See also the Maharal (several hundred years before Hegel)in Gevuros Hashem 5, where he says that it was necessary that Avrohom incubate his kedusha in the seviva of, and as a scion of, Terach, as was the case for Klal Yisroel in Mitzrayim, Chizkiyahu from Ochoz, and Yoshiah from Amon. The Maharal says that this is necessary because rah and tov are both brios of Hashem and are necessary to create a perfect unity. As translated by Betzalel Naor in his introduction to “Kook Orot, ” (Aronson, 1993) it goes like this:
“It has been explained that though Terah was an idolater, the side of holiness issued from him, being as the opposites proceed from one another. The main explanation is, as we said, that it is seeming that the opposites proceed one from the other, because of the relation and synthesis they have together. The two opposites perfect a total which lacks nothing; it is a thing and its opposite, so nothing could be lacking. This is the concept of unity, which by definition is the all, outside of which there is nothing.....the farther apart the poles, the more seeming that they derive one from the other, for in this way they are the whole.”
Anyway, the point is that according to the mefarshim brought above, the rules aren’t going to change. If someone tells you that this or that minhag or halacha no longer applies because Mashiach is on his way or is here, just remember that this is not the first time you've heard this nonsense; we went through it with Shabsai Tzvi and the Frankists already.