This Research Full Paper addresses the definition and implementation of Computational Thinking (CT) in K-12 education. CT is the focus of ongoing debate about the future of computing in schools, and this poses a number of challenges. Early discussions on the topic were plagued by vague and all-encompassing definitions of the term, which raised awareness of a need for school learning focused on emerging computational systems and their impact on society and the lives of citizens, but failed to address what should actually be included in the revised curricula. As some of those issues have been addressed, a number of problems remain. This paper analyses some recent and future developments in the field of computing, and expands the discussion on the vexed question of the nature and limits of computational thinking. We ask whether the current mainstream literature and curriculum for CT is well positioned in terms of the future towards which computing is heading. We conclude by summarising the implications these questions have for the future development of K-12 curricula and teaching practices.