According to the terms agreed to in Islam, they should both kill each other.
In fact, it is Osama Bin Laden's ambition (as an Islamist) to eliminate the House of Saud (the Wahabis).
The guy is too stupid to do the job, however, having thought the route to success ran through the World Trade Center.
The Wahabis ARE Islamists. They are just the oldest branch, and have been thoroughly "corrupted" by the power and money they have gotten from their alliance with the Saudi government.
Osama has no real doctrinal disagreements with the Wahabbi establishment in SA. He just thinks his group should replace theirs becauuse they have become corrupted by contact with the West.