why are you so sure? not questioning, just would like to know a source.
Because I'm at the end of all but one tree and haven't received extra invitations from any of them, pictures for the 15 we currently have were up on day one (probably taken from the folders) so there are a few possibilities
#1 The invite requirements are very high and/or specific so we haven't received them.
#2 They are in the game but are currently disabled.
#3 They will be patched into the game in future.
I'd love to believe that its number 1 but outside of system permits and extreme feats of exploration I like to think I've done most aspects of the game to a fairly thorough degree, if the invite was combat or trading based I suspect i'd have it or they deliberately made some engineers that require Elite etc, which wouldn't make much sense because the time commitment would be enormous and most modules already have a rank 5 available.
We are basically missing weapons and thats it from the major modules, Beams, Plasma, Cannons, Pulses, Bursts, Frags, Missiles, Torps, actually every weapon other than multi-cannons is missing, almost every other module is in.
If they are going to have 30 they will need to invent some stuff for them to mod or there is gonna be a great deal of deadweight, especially strange if you consider rank 5 FSD was available from two sources straight away.