House of the Dragon has been promoted as the “beginning of the fall” of the House Targaryen, making way for its descendants (Daenerys and her brother Viserys)
House of the Dragon draws on George R. R. Martin’s 2018 novel Fire and Blood, which serves as a prequel to his A Song of Ice and Fire series of novels
While Bloodmoon didn’t survive, House of the Dragon certainly looks like it will. It’s not known how many seasons have been planned, story-wise.