I successfully extended at MTT 2 weeks ago. I was not required to furnish a booked ticket, but I was asked verbally whether I planned to depart by Jan 2022. Of course, I said yes. 10 minutes later I had a fresh stamp thru Jan. They also said verbally that this was the last extension.(But they have said that before)
No countries open nearby. Keep an eye on Langkawi, Malaysia and Phu Quoc, Vietnam. Those are on the radar for opening up to int'l arrivals this winter. Not sure if they will allow visitors from Thailand...so don't bet on these...just keep them in mind just in case. Also, neither of those places have a Thai consulate. Easy visa runs are a thing of the past now. :(
As a more stable sense of "normality" is reached, yes, these programs will be eliminated. In the past, short-term visitors who wanted to extend for additional "short visits", had to exit to neighboring countries to prevent an overstay status. The pandemic made this practically impossible. It's admirable that Thailand offered this as a stop-gap measure(whatever their motivation is). But it will not continue. Even they are unsure as to when, which is why the program only ever gets "resurrected" for two months at a time, and often at the last minute (one to to weeks before it was scheduled to be eliminated).