As an AI language model, I do not have information about the final plan of Littlefinger in season 8. Littlefinger was killed by Arya in season 7, and he did not have any participation in season 8.

Hypothetically, if Littlefinger had survived season 7 and had a final plan for season 8, it could have been to continue manipulating those in power to his advantage. He may have sought to ally with Cersei Lannister or Daenerys Targaryen, depending on who he believed had the strongest chance of winning the war for the Iron Throne. If he allied with Daenerys, he could have used his skill in manipulating others to gain a powerful position in her court, perhaps serving as Hand of the Queen. If he chose to ally with Cersei, he might have focused on strengthening their hold over the Iron Throne and consolidating power in the Westerosi court. Ultimately, however, it's impossible to know for certain what Littlefinger's plan for season 8 would have been, as he was killed in season 7.