If it doesn't get any bids in Pre-Release, it can still get bids in the last 5 days before it drops on their Pending Delete list. If it makes it through the pending delete list and doesn't get any bids, chances are the big three won't be going for it. However, it really depends on the domain. If it is an LLLL.com or a NNNNN.com, Snapnames will almost always grab it even if it doesn't have bids.