Under the existing system you'd buy the flights, arrive then an Immigration Officer checks that you meet the requirements. The requirements are not changing just when/where the check is done.
You need to cover onward travel for your airline (~$15) then spend time at Immigration and pay 1900B for an extension, very little difference in price but the 90 day Visa (£60) is much more convenient.
You are wrong, the 90 day Non-O is the retirement Visa and the 12 months that follow in Thailand is not a Visa, it is an Extension of Stay (based on retirement)