@Nick ******
, sadly you and many many THOUSANDS of foreigners here on the amnesty will have to wait to see what happens once they get the borders, neighboring countries and thai consulates in them open & what the new entry requirements might be (IF there are any).
Now in re-reading your post you "might" (as in perhaps) have a chance for an extension
if your half thai child is born soon enough, you can cancel this Non-B extension and then immediately apply for a 60 day visit thai family extension,
that would buy you two months (so past the amnesty) and let you see IF any other opportunity for another type of extension comes up (marriage, owning the company etc)
That's the only thing I can think of.. Otherwise if you just cancel this extension and go on amnesty you're done, and you WILL have to leave the country to start any other process once amnesty is over