Plenty of questions, which I hope you have already discussed with your wife:
- There is absolutely no guarantee that exchange rates will stay stable or continue to favor you in the long-term. What are your plans to mitigate this risk?
- Have you researched the immigration process (costs and timelines) to obtain legal permanent residency in Brazil?
- If your wife is a Brazilian citizen holding a US green card, a permanent relocation to Brazil may cause her to lose her US permanent residency. Is this applicable to your case? If yes, is this something you are prepared to accept?
- Have you researched the Brazilian legal restrictions on foreign nationals' bank accounts and real estate ownership? Due to FATCA, in my home country, banks are hesitant to allow US citizens to open bank accounts. You have to personally know the bank manager to MAYBE get an exception. On the other hand, due to my country's laws, foreign nationals cannot actually own real estate except condominiums. They usually put the titles in their spouses' names. Does Brazil have similar restrictions?
- What are your plans for your son's education? Have you identified Brazilian school(s) that meet your expectations and budget?
- How easy is it to move money from the US to Brazil and vice versa? Some countries like China have extremely strict capital controls.