Old socket prices never bottom out when new sockets come out on Intel. They are masters at controlling production and distribution, and see no sense in competing with themselves by discounting old stock.
Trust me, 3770K will still be the same price in a year where available, and used prices of upper-limit 1155 chips will remain high as well. Even your 2500k will retain solid value for people looking to jump out of lower-tier i3s / Pentium Dual / Celeron setups (for which the upgrade is pretty substantial, particularly if they have a board that can run the MP).
Outside of a few things that can take advantage of HT to a decent degree (mostly encoding), an O/C 2500k will game just about as well as a 3570/3770 anyway, sometimes even better if you have a great chip vs. a 3xxx that hits a wall at 4.4-4.5 due to crap TIM. Hell, an O/C 2500k may well game better than a stock Haswell i5/i7 depending on how the final benches work out.
Cliffs : keep your 2500.