I don't care. Worrying about such long timescales induces a sort of paralysis. The solution to uncertainty about truly fundamental questions of existence is to work on fundamental math and physics, to figure out where matter comes from, whether other dimensions exist and are accessible etc. If you just feel discouraged by the pointlessness of existence, that's just a sort of vertigo or cognitive overload. It's better to pick something you like and scurry around exploring it rather than being stuck in intellectual catatonia. The best cure for this is to engage in something you find physically enjoyable; rebooting your sense of physical autonomy helps to shake off the cognitive paralysis. Go for a walk, jump around to loud music, eat some of your favorite food, or amuse yourself with comical imagery so as to alter your mood. The seeming futility of existence doesn't matter because it's on too large of a scale for you to experience or impact; the feeling that it overrides all other considerations is just a feeling.