What are the consequences of a Thai spouse's death for a Non Imm 'O' visa holder in Thailand?

First lets address the situation of a thai spouse's demise while you're on a year long multi-entry Non-O visa (that you got from a thai consulate in another country).

In that instance you can still bounce in and out every 90 days on the visa until it expires.

Secondly let's address the situation of a thai spouse's demise while you're on a yearly extension of stay (from the immigration office inside the country).

In that instance you can stay on that yearly extension until it expires.

At that time you'd have to change the reason for your next extension to either :being over 50 (retirement) or some other reason, and it goes without saying you'd have to meet the financial requirements of that new extension