agree with what Daisy says. Elite visa is entirely legit, and it looks like they will be the next group allowed in. The process takes 6-10 weeks, so not too long.
Seems pretty logical to me, their status in law is the same as a tourist. People who have lived in Thailand for a long period on yearly granted visas (which effectively is what the retirement visa is) and have no status to work can’t be anything else.
It is for people who have the funds, are in Thailand and want to remain here. There are relatively few other options beyond volunteer, ed and retirement visas.
You just need to have started the process prior to 26th. As long as it all goes through ok (ie you actually have money and obtain clearance) you won’t have any problems or need letter.
I used Trailfinders to get all my visas and they can help getting a business visa as long as you fulfil all the requirements but they can’t help you start a business, obviously.