Since you asked it, I did check with Cigna. Outpatient coverage can be added to my current policy. The lowest coverage they give is US $10,000 and the highest deductible is a little less than US $2000. That would be an expensive add-on, so I'm not going to do it unless there is no other choice.
What I intend to do is open a new Thai bank account, put 40,000 baht into it, and just let it sit there so it becomes obvious to immigration that I can self-insure outpatient coverage. Of course, there is no way to know now if that would be acceptable to immigration if outpatient coverage does eventually become a requirement for the O visa extension.
I don't know, but I doubt it. If type O visa holders are not required to carry health insurance, then Elite Card holders would likely be exempt too - for the time being. The least expensive Elite Card is 500,000 baht, and there are much more expensive options available. If you want to spend 1-million baht for an elite card, you get a 20 year visa, renewable every 5 years. Of course, at retirement age you may not even still be alive 20 years after getting that card. Then again, it might actually be worth it considering many of us now have to keep 800,000 baht just sitting there in a Thai bank account anyway.
People who have the money to pay for the Elite Card would be highly unlikely to be the type that skip out on medical bills.