For those thinking that this is just Java and Flash all over again: Here's the relevant blog post from Steve Klabnik explaining why this is _very_ different:
Just imagine running `VACUUM` on that table that wrote 1M rows/seconds for 300 years and now you need to vaccuum quick because the transaction ids will wrap around next year...
https://words.steveklabnik.com/is-webassembly-the-return-of-...