If it happens, it may not necessarily be this year's draft.
They have up to July 15th to work something out before it becomes 'this deal or nothing'. The Raiders could possibly put off signing a deal until after the draft so that they don't have to give up any picks until next year, with the hope for them being that next year's picks will be lower.
Mind you, that could backfire and they could actually wind up giving away an even higher pick instead, but teams tend to bet on themselves (same as players do).