In fact, it was quickly superseded by Inferno and Limbo, in AT&T race to compete with JavaOS, which is why Dis also got initial support to convert between bytecode formats.

Overall, after the sale to Vita Nuova, one could assert Inferno has had much more real commercial use than Plan 9 has ever had outside Bell Labs.

Yet Plan 9 fans seldom acknowledge it was a transition between UNIX and Inferno.