That is very incorrect. If the employer revokes the I-140, USCIS will send an RFE or NOID very quickly. And if they do that and you don't provide evidence of another "same or similar" job or job offer, your application will be denied. See page 3 of the 2003 AC21 memo: http://www.usavisanow.com/8-13-03-140-485.pdfJackolantern,
You are right. After I-140 gets approved, the company can still revoke my I-140 case. But, here is the discussion basically saying that REF will NOT be sent out till I485 is adjucated.