If it comes down between releasing Evan Bourne, and releasing someone else, then I think WWE should just let him go.
Otherwise, I think they should keep Bourne on for awhile more. Even if they have no plans to push Bourne, they could just use him as a jobber. His biggest strength is his ability to sell moves like death. Maybe punish him by drafting him to the SmackDown brand and making him exclusive to SD, and never have him show up on RAW at all. Use him as a featured jobber, so that other guys like Kidd, Ryder, or Riley who have a bit more of an upside won't have to be used in this role.