When I went to Chaeng Wattana a couple of weeks ago it was quite busy except for the section to extend tourists visas / exemptions. I think the intention of the amnesty was to provide a solution for tourists who've been stranded here for whatever reason (who mostly wont care what happens after July). It's not about foreigners who live here being able to ignore visa requirements for some period of time.
depends where you are coming from. i can't see arrivals from western europe / north america being accepted for a long time. if coming in from asia, should be much sooner, but not by the 1st of june.
Millions of Thais have lost their jobs and have no income to feed, accommodate, and medicate themselves and their families right now. More have killed themselves because of the lockdown than died from or with covid. How can you hope for that suffering to continue?
I think visitors from particular countries will be allowed in whenever that country ends their lockdown plus a few weeks. That should be soon for most Asian countries but a lot longer for Europe and North America.