No doubt 3,000 is going to happen. He has stated this as a goal and barring injury he's four years away from it max, only three if can average 190 hits during that time. 42 is old but not for the ball players like him who keep themselves in excellent shape. Besides, even if his play tails off over the next couple years, a dozen teams will sign him simply for the bonus Japanese fanbase that still comes with him. Teams who value Asian TV revenues will probably continue to sign him as long as he wants to play.
3,000 will guarantee a first ballot. Over the last 20 years, guys who reach the big milestones (3k hits, 500 HR, 300 wins) and don't have steroid accusations nearly all get in first ballot. If Craig Biggio gets the nod his first time out, we will probably be able to etch that theory in stone.