Yeah, you may well be right. But if the land borders do not re-open, the Thai government will have to extend the visa amnesty. The meeting is (I understand) planned for 26 June, so we should know then.
is referring to the borders with neighbouring countries that will hopefully re-open in July to allow people on O/B/tourist visas to get new visas and then re-enter Thailand (not the border pass which is just for citizens of those countries to go home).
Yeah, it would be good if they allowed that. I know of some teachers who have been told they should be able to get their non-B visa from Laos next month, but so far no indication of whether that will happen.
There are thousands who need to border bounce to get a new entry or who need a new B or O visa. It's not been possible to do this and won't be until the borders reopen. I haven't seen any indication that those affected will be denied this option and will be forced to go back to their home country, but maybe that will happen. We should know soon as a decision re the amnesty will need to be made in the next few weeks.
Can't say I'm optimistic, although Laos has had 0 cases for a while, but as my family are stuck in Laos, I'm hopeful. But in respect to the OP's question, if the border remains closed, the amnesty will be extended.
Do you want to go back to the UK, or just get a new visa/entry? Either way, we should know soon if the amnesty will be extended. If the borders with Laos and other nearby countries open, you can hop across and get a new visa/entry. If flights start again, you should be able to re-book to go back to the UK as FinnAir have only cancelled as all flights from/to Thailand are still restricted.