Can I substitute chocolate chips for cacao nibs in a cookie recipe?
You can.

It will be a different cookie, but chocolate chips are conventional in chocolate cookies -- more so than cocoa nibs in fact.  I assume they're simply stirred in to the mix after the other ingredients.  The texture of the surrounding cookie (and the cooking time) may be affected a little, but only within normal batch-to-batch variation.  

If the bittersweet chocolate is added in the same way (as opposed to melted), I'd just scale that up. You may instead want to use a contrasting chocolate.  You could even replace the nibs with chopped nuts.