My well seasoned advice.
Do NOT retire in Thailand.
Thailand offers no residence security to retired expats and never will.
Instead pick a country in Latin America that offers an easy path to permanent residence and/or citizenship and also preferably right to buy land, and access to national health care programs.
If you INSIST on Thailand, do at least one test run of living in Thailand in a normal non tourism way for at least three months before deciding about assets back home.
About selling homes back home, that depends on the financial and personal situation of the individual. There is no one size fits all advice for that.