Normally the term Vaporware is used to refer to a product that SEEMS like its never going to come out. Your only proof that it isn't ever going to come out is when the company says they canceled it or the company goes under.
Clues that a product is vaporware:
missed the original published release date
missed the next revised published release date
stopped publishing the release date
stopped talking about the product in press releases
removed all references to product on website
The biggest sign of vaporware is that the company NEVER acknowledges that the product is canceled. They just stop talking about it and stop working on it. It justs turns into vapor.