This ostrich/kosher issue has been debated for thousands of years by Arab and Jew scholars; unfortunately, the issue is clouded, and it has been obfuscated by translation error. Allow me to summarize, if I may, many centuries of ostrich/kosher research:
"Ostrich" was specifically forbidden in Leviticus:
יג וְאֶת-אֵלֶּה תְּשַׁקְּצוּ מִן-הָעוֹף, לֹא יֵאָכְלוּ שֶׁקֶץ הֵם:
אֶת-הַנֶּשֶׁר, וְאֶת-הַפֶּרֶס, וְאֵת, הָעָזְנִיָּה.
יד וְאֶת-הַדָּאָה--וְאֶת-הָאַיָּה, לְמִינָהּ.
טו אֵת כָּל-עֹרֵב, לְמִינוֹ.
טז וְאֵת בַּת הַיַּעֲנָה, וְאֶת-הַתַּחְמָס וְאֶת-הַשָּׁחַף;
יז וְאֶת-הַכּוֹס וְאֶת-הַשָּׁלָךְ, וְאֶת-הַיַּנְשׁוּף.
יח וְאֶת-הַתִּנְשֶׁמֶת וְאֶת-הַקָּאָת, וְאֶת-הָרָחָם.
יט וְאֵת, הַחֲסִידָה, הָאֲנָפָה, לְמִינָהּ; וְאֶת-הַדּוּכִיפַת,
But this was in reference to "ostriches" of that era ( בַּת הַיַּעֲנָה ) - a sort of proto-Ostrich of the Judean desert unlike the modern bird of Africa or Morgan Hill, California. The Proto-Ostrich was, by necessity, lumped together with other "winged things." From context, we can rest assured that these "ostriches" could fly, and did not chew cud; these traits automatically disqualify the proscription against the bird of our own era. The Levitican proto-ostriches were more regular birds-of-prey, accordingly, were governed by that rule-set.
But even in Hebrew, ( בַּת הַיַּעֲנָה ) is not even the same word "ostrich" יען הנגב used to describe that flightless edible bird that resides in Africa, nor in modern Israeli zoos - because it is a different animal.
Furthermore, archaeologists who have studied various translations of the old texts do not even agree that the proscription against this mystery-bird " בַּת הַיַּעֲנָה " was ever in reference to what we call Ostrich today (evolutionary changes notwithstanding). Some speculate that it refers to the dubious "Arabian ostrich." Evidence for the existence of this bird is sparse; biologists disagree on fossil identification; it is plausible that no such creature ever existed. At least one Jewish historian prefers to translate יען הנגב as "Arabian Vulture" or "Pharaoh Eagle Owl", an extant species that fits more within the context of the original verse (which was discussing owls anyway).
On deeper study of more recent text
وَمَا مِن دَآبَّةٍۢ فِى ٱلْأَرْضِ وَلَا طَٰٓئِرٍۢ يَطِيرُ
بِجَنَاحَيْهِ إِلَّآ أُمَمٌ أَمْثَالُكُم ۚ مَّا فَرَّطْنَا فِى
ٱلْكِتَٰبِ مِن شَىْءٍۢ ۚ ثُمَّ إِلَىٰ رَبِّهِمْ يُحْشَرُونَ
stating specifically that birds live similarly to humans; they have society; and they walk bipedally. There is no proscription against eating these creatures. The text goes on to state that there are no exceptions to this rule; and that no rules have been forgotten to be mentioned in the text; thus closing the ostrich/kosher hole.
Again, we see the نعامة عربية is the same root word as the modern ostrich, and in this writing system, there can be no ambiguity between owl / ostrich. Hence, the religious doctrine is uncorrupted by centuries of translator-errors.
One last possible interpretation is that Ostrich was formerly forbidden to eat, but later evolved into a creature in accordance with kashrut. In the thousand or so years between the writing of Leviticus and the writing of the Quran, ostrich learned to chew cud - thus satisfying the conjunctional rule of cloven hoof, cud-chewing land animal. Thus, evolution took place - making the ostrich the only animal to change its characteristics through evolution in such a way as to cross the Kashrut boundary since the foundational rules were set forth. Evolution is a fact; and as we know, any ruleset has edge-cases; but the ancient ostrich, who was only barely on the edge of verboteneFrucht, managed to evolve across the barrier. Ostriches 2.0 now qualify as kosher.
Pig has never been upgraded (by act of God or natural selection), and so it remains, in perpetuity, unclean.
 Tanakh (Hebrew Leviticus). English Translation: Jewish Publication Society of America (1917).
 Aharoni, I. (1938): On Some Animals Mentioned in the Bible. Osiris 5: 461-478.
 Quran. "Cattle," Surah 6:38. English Translation: Abdullah Yusuf Ali (1938).