cos is already on sale at $21. Take a look at imperal's kearl project:

the projected total cost to build is over $31 billion, 10% higher than the current total market value of Syncrude. Kearl has similar resource base as Syncrude. If cos does go down to $17.50, it would not surprise me that someone comes along and takes out cos at 30% premium (just $23 a share), saves all that trouble to build a mine and gets all that oil sands reserves for free!