You will lose your Points upon your death, and your estate, successors and assigns have no property rights or other legal interests in such Points, except under this circumstance:
Cash Rewards Option-If we receive a written request within one (1) year of your death from the executor or administrator of your estate, along with evidence satisfactory to us of your death and the identity and appointment of the executor or administrator, we can allow Points remaining in your ThankYou account to be redeemed for Cash Rewards. Contact the ThankYou Service Center at 1-800-THANKYOU (1-800-842-6596) for more information.
IMO-not such a great option but a lot better than Chase Ultimate Rewards and American Express Membership Rewards whose currencies you cannot pass at all upon death.