Chicken : I think they will surely lose value, at the end of the day I see them as a commodity, few people will really want to use a domain name like 0Q5.com for their website (characters pulled out of the air!) most go for around $15 simply because thats the market value for them, they are unlikely to be used, its just that their fairly in demand just to be sold again. As with any commodity if the markets flooded with them then their value falls.
Hostlead : you have to click on "newest deletions".
I only use them when I have a longer name that it matches. At that point I generally register the long name and point it to the three letter. The best example I know of anyone using the mixed three letters is EV1.net. DV2 also seems to be working pretty well for them. I have under development WV5.com for Web Vision 5 where I also own webvision5.com. Not great, but workable. Overall, they are not worth premiums, but at $10 I am comfortable making the purchase.