I also seem to remember people prebuying the C&C CKG and had to wait years and years before it ever came out. (Did it ever come out? It's been so long, I stopped caring.)
Just a couple of things to mention here:
1. The CKG is being released by Troll Lord Games "as we speak" -- the digest sized hardback is out already and pre-orders for the regular hardback are to be filled within days.
2. A common misconception about C&C is that the CKG is needed in order to play. C&C is a complete game without the CKG, which is simply a bunch of optional expansion rules. I've played C&C since 2003 with no need for any books other than the PH
and Monsters & Treasure
3. As far as I know no pre-orders were accepted until very recently, when the CKG was essentlially done and in final proofreading/layout stages. I don't think that anyone paid and then waited for years.
However, I understand your concern. I've bought products from companies, only to have the stuff never get completed and often see the company vanish without a trace. Sometimes I get angry about it, but more often I just get sad that they tried and couldn't deliver. With all of their publishing credits I don't believe that Goodman Games will fall into this abyss so I'm willing to gamble, but I can certainly understand why others might not be so willing.