No, the known information he has shown was that "something like this" worked, in the same way that "something like Cashmere Mafia" worked, but Cashmere Mafia didn't.

The assertion "this other MMORPG with a classic server worked so every MMORPG with a classic server will likely work" is exactly as faulty as "this TV show about women in the city living glamorous lives worked so every TV show about women in the city with glamorous lives will likely work".

There's also probable evidence that it would fail if you look at 1) the low server populations we have now and 2) the even lower server populations on the private servers which fulfill this need.