I edited my initial response to make more sense. Going through Bail, the lineage is right on the money. He's the unproclaimed King of Alderaan, his wife the Queen. So, Bail and his wifey die, that indeed makes Luke the king and Leia's already the Princess, leaving the future Queen position open to Mara Jade, and the Prince title to Han Solo, I'd imagine.
Betcha didn't know I was that big a SW fan, did ya? 😛
Where's Yuxa when you need him!?!