people are demanding more. not necessarily getting more than the spreadsheet price. i hear people have sold them max 13 keys atm.
 
Well you can speculate on the fact that it won't drop any more, but tf2 trading is generally the buyers market. You might still have one for sale a year after it stopped dropping, but noone can guarantee that there will be demand for it just because there isn't that many on the market any more. There is a possibility that most people who want to get one will own one by then you know, and tf2 doesn't get new players any more who would pay a lot for it just because they weren't around earlier.