the problem to me is not scale but power level of the capital ships. they are chalk full of turrets and launchers and iirc the only way the rebs actually killed a couple was to make them crash into each other not by actually shooting them down.

i think the capital ships are better as a doom tracker for a rebel scenario ie the rebels have X turns to complete a scenario before the star destroyers gets in range or the rebs have to take out a fleeing tie fighter before it makes it back to its destroyer. It could also be part of the battlefield that if the rebel ships enter a certain zone they are in range of a destroyer and take fire kind of like the rolls for collision.

my biggest worry for x wing is a lack of ships after wave 2. they have pretty much hit all the iconic ships in the prequel and there isnt much left for wave 3 and beyond.

Now, what do you mean by "Wave Two." I consider the first release to be Wave One, the upcoming Falcon/Slave/A/Int. to be Wave Two and the as-yet-unknown followup to be Wave Three. Three is still golden, as it will have B-Wing 100%, TIE Bomber 95%, and Lambda shuttle about 85%. What ship #4 is, no one has any idea whatsoever. If Wave 3 is successful, there's still a buttload of options, granted EU, but GOOD EU: Z-95 Headhunter, TIE Defender, Skipray Blastboat, Outrider, E-Wing etc. There's still OT goodness to be had!

In addition to the ships you mentioned, there are plenty of other potential products, including:

Scenario books, Campaign Rules, New pilots. Rules for attacking bases, and outposts. Atmospheric combat, ground attacks and attacks against capital ships. Frieghters to be escorted (or attacked).

An Imperial Star Destroyer reportedly has 60 Ion Cannons and 60 Turbo lasers. The X-Wing game is too small in scope to really deal with players attacking and destroying an entire Star Destroyer. An ISD carries 72 fighters (36 TIEs, 24 TIE-Int and 12 TIE Bombers). Even without the fighters, it would probably take a force of 40-80 X and Y-wings to take out an ISD. Using that many fighters isn't practical (or affordable).

I think that scenarios involving ISDs would involve 4-8 rebel fighter attacking a portion of the ISD. Their mission could be to destroy some turrets so the strike fighters can attack safely, or to destroy the shield generators on top of the command section. The point is, if its a big objective/target, the X-Wing game is scaled such that the scenario involves the play just playing out a piece of the operation with limited objectives.