the universe seems to be metastable
Well, that's sort of uplifting somehow. I remember in high school I read a book about the potential ends of the universe, and metastability didn't come up. Instead they said eventually, everything reactive will react with everything else until the whole universe reaches a kind of energetic homeostasis: which would manifest as an infinite expanse filled with light-year long blocks of iron - forever.
Actually, I used to read that book in the library instead of going to lunch... I was a strange kid.
The results are in fact there. You can check that we are very close to the stable/metastable frontier, but on the metastable side. You can find the figure in this paper, page 18.
You book seems... let's say old ;)
It was probably 20 years old when I read it, maybe 14 years ago. And anything but comprehensive - more pop-science. It was a weird book really.