I would not be surprised if we have over 100 Star Citizen members be the time the game officially launches. We already have 60 members signed up for COTP on the Star Citizen Organization page. Once more information about the game becomes available and we start actively recruiting in the upcoming modules like dogfighting is see to possibility for huge numbers even before the game officially launches.
I can imagine over 300 members if we play it right. Time will tell.