Lucas tem o direito de se tornar o rei de Naboo?

Não. Naboo tem uma monarquia eletiva - o líder é eleito, como é dito várias vezes nos prequels. A genética não lhes dá o direito de governar. Para provar isso, aqui estão algumas citações do script:

Episódio 1, Palpatine:

To state our allegations, I present Queen Amidala, the recently elected ruler of Naboo, to speak on our behalf.

Episódio 2, Amidala:

I never thought of running for elected office. But the more history I studied, the more I realized how much good politicians could do. So when I was eight, I joined the “Apprentice Legislators,” then later on became a Senatorial advisor, with such a passion that, before I knew it, I was elected Queen. Partly because I scored so high on my education certificate, but for the most part it was my conviction that reform was possible. I wasn’t the youngest Queen ever elected, but now that I think back on it, I’m not sure I was old enough. I’m not sure I was ready.

Não, ele não tem direito a nada. E se Lucas pode ser eleito ou não está em questão. Por um lado, nunca houve qualquer menção a um rei de Naboo. Os três relatos que conhecemos são todas mulheres servindo como Rainha.

1. Rainha Amadala

2. No episódio de Clone Wars "Crisis On Naboo", quando o Supremo Chanceler Palpatine retorna a Naboo para o Festival das Luzes, ele é saudado pelo Senador Amadala e pela atual Rainha de Naboo.

3. Some twenty days after the Battle of Endor—which resulted in the defeat of the Empire by the Alliance to Restore the Republic—the Royal House of Naboo received the visit of Princess Leia Organa of Alderaan, who had been sent by Mon Mothma, Chancellor of the Alliance. In the royal palace's throne room, Organa met the then-Queen of Naboo, Sosha Soruna, and asked for Naboo's support in the establishment of a New Republic and the restoration of the Senate. The queen heartily accepted Organa's offer, claiming that the Naboo felt great shame over Palpatine's actions. - Wookieepedia - Naboo (attributed to - Star Wars: Shattered Empire II)