I do like the angle that Snoke uses Ben Solo to unite the Imperial remnants together by being the heir to the empire.

I also think it would emphasize an interesting dichotomy between the First Order and the New Republic. The Empire fell apart because their figurehead, the Emperor, died, leaving no clear ruler. Snoke could use Ben Solo, grandson of Darth Vader, to reunite those scattered factions of the Empire to a common cause. Then, when they destroy the Senate, the New Republic falls apart because they have no clear leadership. But Leia believes Luke, the last member of the Jedi Order, would have the power to reunite the Republic and work together to stop the First Order.