We all recognise when the occasional top-tier domain is offered for sale but I can't imagine these domain owners responding to the general 'have lots of cash' type postings. Why would you bother, you know the best response your likely to get is "Well its only worth such-and-such to me" and that's only if the potential buyer has any ready cash at all. Besides, if you are holding valuable domains you all ready know where to sell them.
I can't imagine these requests have much to do with domains dropping in the future, more a case of pretending to be at the 'Top-table' . Those that post a specific domain request are probably genuine but don't expect any offers to reflect the hyped heading.
I liken it to a buyer posting I want to buy a car/automobile for Big Bucks, No model, No spec - yeah right. Asking for .com short/pronounceable only is akin to saying it must have four wheels, and showroom condition. We call them tyre-kickers in the UK