Your question suggests to me that you still don't get it: nothing in Plan 9 -- not the shell, not the ability to issue command lines and get stdout and stderr back -- depends on vt(1). vt(1) is used only to communicate with (tty drivers on) other OSes, over the network.

Just as most of time, a user of OS X has no need for an X server, most of the time, a Plan 9 user has no need for vt(1) or for ncurses.

I'm not suggesting you give Plan 9 a try BTW: on its best day ever, it had fewer than 1000 users, and if it was ever going to break 1000 users, it would have done so by now. The whole OS (excluding some fonts) has been available under an OSI- FSF- and DFSG-approved license since 2002.

So for example, Plan 9 will almost certainly never have a web browser capable a delivering a satisfactory experience on more than half of the 1000 most popular web sites -- because porting such a web browser to Plan 9 would cost 10s of millions of dollars in programmer time, and no one is going to spend that money to get fewer than 1000 new users.