First, some background.
There are several errors in your question that need to be addressed before I can answer your question directly:
- You falsely equate the yemoth mashiyahh and `olam haba as if they are one and the same.
- You are under the assumption that in `olam haba righteous yehudhim and goyim have the same or similar standing and even "rule" together.
- Subsequent to 1 and 2, you assume that goyim "inherit" land either in eress yisra'el or in some other nation.
Dealing with them in order, they are corrected as follows:
[1] Whereas the nature and contents of the yemoth mashiyahh are described by the Biblical prophets, nothing is known or perceived about the nature or contents of `olam haba. The Rambam, in the Mishneh Torah (Hilkhoth Teshuvah 8:7) says this explicitly just as it is clearly stated by Hazal:
...It has already been made known to us by the ancient Sages that man is unable to apprehend and understand the goodness of `olam haba as it actually is, and man does not know its greatness, its beauty, or its essence - only HaQadhosh Barukh Hu alone. And all of the good things that the prophets of Israel prophesied to the people, they were only those things which pertain to the physical body, which will be enjoyed by the Jewish people in the yemoth mashiyahh, that is, in the time when the sovereign kingdom will return to Israel.
But the goodness of the life of `olam haba, it has no estimation or likeness to anything in this existence. And so the Biblical prophets did not attempt to describe it lest they lessen its greatness through illusion. This is what Yeshayahu said, "no eye has seen it - no one beside you, God - that which He prepares for the one who waits for Him" (64:3). That is to say that the goodness that that the prophet's eye has not seen, God prepares it for the man who waits for Him. The Sages said, 'None of the prophets prophesied about anything except for the yemoth mashiyahh, but as for olam haba "no eye has seen it - no one beside You, God."'
It is clearly seen, then, that the yemoth mashiyahh and `olam haba are certainly not to be equated, as they are not the same at all.
[2] This next error is a common misunderstanding and is rather complex. It involves a common equation of every type of righteous non-Jew. However, according the Rambam in the Mishneh Torah, only righteous yehudhim and a group known as the hasidhei umoth ha-`olam receive a portion in the spiritual life of olam haba. The rest receive blessings in this world and many in the yemoth mashiyahh. This can be seen clearly when taking in aggregate all relevant statements of the Rambam on this subject as written in the Mishneh Torah. The first of which is found in the laws of receiving converts. There (Hilkhoth Issurei Bi'ah 14:3-4) he says:
...Just as we inform [the prospective convert] of the punishment for violation of the misswoth, so do we also inform him of the reward for observing them; and we inform him that by performing these misswoth he will merit the life of `olam haba...and we say to him 'Know that olam haba is not hidden away for any except the righteous ones, which are the nation of Israel...'
In other words, one has to be connected in a real and halakhic way to the Jewish nation in order to receive life in `olam haba. This is explained in the eighth chapter of Hilkhoth Melakhim Umilhhamoth in the Mishneh Torah. It is here where many have misread the Rambam. When the Rambam says "kol ha-meqabel..." he is referring to a ger toshav dawqa - which is only received in a time when we count the yovelim (cf. Hilkhoth Issurei Bi'ah 14:8) and their reception has to take place in front of a court of three (see Hilkhoth Melakhim Umilhhamoth 8). Anyone else among the nations who is righteous is promised provision and blessing in this world in exchange for his deeds (cf. Hilkhoth Shemittah WiYovel 13:13), but unless he attaches himself to the nation of Israel and becomes a hasidh me-umoth ha-olam, such a one will not receive a place in olam haba. Read these things carefully and critically wa-du"q.
It may not be popular or the party line within modern Judaism, but this is - le-`aniyuth da'ati - the accurate view of the Rambam (and it appears to be the view of Hazal as well).
[See also, Hilkhoth Teshuvah 3:5 and Hilkhoth `Avodhah Zarah 10:6, et al]
As for Jews "ruling the world" in the future under the mashiyahh, this idea is the fantasy of anti-Semitic groups and some Christian sects. While the Jewish people will collectively exercise sovereignty over eress yisra'el and will have political dominance over the surrounding areas due to their subduing their immediate enemies via warfare (cf. Hilkhoth Melakhim Umilhhamoth 11:8), there will be no world domination by the Jews. Rather, the nations of the world will be persuaded by the wisdom of Israel's righteous king to work together for peace and prosperity, each human being acknowledging God and His sovereignty over the world.
[3] In the yemoth mashiyahh, there is no inheritance of any land in eress yisra'el for anyone except the shevatim and those who have converted to become full Jews. The future division of the land as mentioned in Yehhezeq'el 47:21-23 is a reference to Jews - both native-born and converts - only. Although I cannot go into it fully here, this prophecy is most likely looking toward an inevitable reality of the Jewish people gathered after a long exile and without proof of parentage, therefore the prophet is stating that there will be a "reset" as it were and those whose tribal affiliation cannot be determined or those who have descended from many generations of converts (converts usually do not inherit land due to their having no tribe) will be given an inheritance going forward. Perhaps a future Sanhedrin will make such a ruling - suspending the din of the Torah in accordance with pressing temporary need (cf. Hilkhoth Mamrim 2), but this is another discussion for another time.
Now, to answer your question.
As for your question regarding a righteous Chinese man in the yemoth mashiyahh and his "inheritance," if such a person in China has any inheritance at all, it will not be in eress yisra'el unless such a person converts to Judaism - thereby changing his national affiliation - in which case he would (apparently) receive a portion of the land per Yehhezeq'el 47:21-23.
If such a person were either a ger toshav (i.e. a hasidh me-umoth ha-olam) or a Jewish convert, then such a person would have a place in `olam haba as well.
If, however, said righteous Chinese man is neither a ger toshav or a Jewish convert, then he is promised blessing and reward in this world and will (perhaps) also be rewarded in the yemoth mashiyahh, but not in `olam haba.
If he is living in China during the yemoth mashiyahh - when all of the nations will be under the justice of the Torah and the sanhedrin of melekh ha-mashiyahh - then I suppose that any land that either he owns or his family owns will be justly handled according to the property law and stipulations of sale at the time such property was acquired by either him or his forebears.
[NOTE: This answer relies on the Mishneh Torah of the Rambam as the supreme, but not infallible, source of Jewish law on any given matter of halakhah. While I do not bring other opinions here (because I do not happen to share them), I do nevertheless respect them.]
