The Energy Charter Treaty (ECT) came into force in 1998 and is currently signed by 54 countries, mostly in Europe and Central Asia. Its purpose is to protect foreign investments from regulatory or political interferences of host State, including through investor-State dispute settlement mechanism (ISDS). A negotiation to modernize the agreement was launched in 2018. On 24 June 2022, after five years of negotiations, the Energy Charter Conference Member States reached an Agreement in Principle regarding revisions to the ECT. Despite a crushing failure to exclude fossil fuel investments from scope of protection, the substantive changes in the modernised ECT represent progress. However, that has not stopped a number of EU Member States announcing their intention to depart from the ECT. A coordinated withdrawal of the EU and its Member States is launched by the European Commission. The sunset clause of Article 47(3) ECT nevertheless hangs as a sword of Damocles over withdrawal options, as withdrawal triggers the sunset clause and protects existing investments for another 20 years. This article discusses the uncertainty around the future of ECT and the challenges beyond.