Orc intergration after the War?

[Mithadan]

Kuruharan: Of course, this also even opens the door to questioning if Elves and Humans were really different "species" or just different types of the same "species."

This issue was addressed, to an extent, by Tolkien. In his "philosophical" writings, published in Morgoth's Ring, he suggests that Elves and Men are, physically, indistinguishable. This explains why the unions of Elves and Men resulted in the birth of children. The difference between the two races is found in the strength of the bond between their "spirits" (the feär) and their bodies (the hroär). In Elves, the bond is strong so that the spirit and body remain joined for the life of Arda, or at least until the body fades leaving only the spirit. For this reason, Elves do not generally suffer from disease and recover from injury far faster than Men. In Men, the bond is weak, so that the spirit and body are easily separated over time or as the result of injury or disease (death).

Morgoth's Ring also contains musings regarding the origin of Orcs. The Silmarillion seems to give Orcs an Elvish origin; that Morgoth corrupted Elves, making the race of the Orcs. Tolkien appears to have later disliked this concept, and suggested that Orcs were of a Mannish origin or perhaps were even corrupted beasts. He never truly resolved this conflict. If Orcs were of Mannish origin, the Silmarillion would require substantial revision as Orcs clearly pre-dated the awakening of Men.

At any rate, if Orcs were of either Elvish or Mannish origin, they would have consciousness and possess spirits, leading to Tolkien's thoughts on redemption. They would also have been able to breed with Elves or Men as is implied in LOTR. So, theoretically, Orcs might have, at least biologically, been able to become integrated with Men after Sauron's fall. Whether they actually did is a matter of speculation. Perhaps, after the passage of time, any physical corruption might have faded so that they appeared to be more like Men. Again, rank speculation.