Ash, I read the ayah you noted from surah An- Nur. I see how the English translation makes it appear that this verse is a command for only single people to marry. So I followed the statement of Allah, "Ask the people of knowledge if you don't know." SO I looked the ayah up in 8 books of tafsir (Ibn Katheer, Al Qurtubi, At Tabari, Tafsir Al Jallalain, Tafsir Al Baghawi, Tafsir Ibn Abi Hatim, Taiseer Kareem Ar Rahman fi Tafsir Kalaam Al Manaan from Abdur Rahman As Sa'adi, and Adwanul Bayan from Muhammed Ameen Ash SHanqinti), a book which deals with the verses of ahkam (verdicts and obligations), and a book of asbab an Nazool (the reason and condition why an ayah was revealed). Not one of these books have stated the opinion you mentioned that it is only permissible for a person to marry 1 time. Not one book mentioned this verse abbrogated polygeny. Rather these books all mentioned that the ayah you mentioned is an encouragement for the Muslims to marry. It also is an encouragement to help and encourage those who you are in responsible for (like orphans, mature children (not pedafiles), servants during that time, etc.) to get married if they have a desire to do so. That's why Allah added at the end of the verse "If they be poor, Allah will enrich them out of His bounty."

So even though this verse encourages single people to get married, it DOES NOT abbrograte or negate polygeny and Allah knows best.

"I don't think so. Homey don't play dat."
Homey Da Clown