In the paper we build on previous work from our group, Browsix ( https://browsix.org ) to provide a similar level of abstractions to WASI (the syscall layer). We've talked about having Browsix support running programs targeting WASI in the browser.
One of the great things about supporting "Unix" in the browser is that it makes bringing a whole class of already written applications and library into the browser. I'm excited to see what people do with WASI, but its not clear to me what a program designed from the ground up around capabilities would look like!