In recent years, social changes have significantly increased the importance of public participation, and technological developments have delivered additional opportunities for participation in political decision-making processes in Western democracies. Nevertheless, despite discussions on this topic, little is known about the desirability of future developments in public decision-making from the viewpoint of policy-makers. Our study provides an evaluation of such future developments by allowing 171 German policy-makers to discuss ten projections concerning future public participation in an online-based Delphi survey. We thus obtain knowledge about expected developments, their desirability and their impact on political actions in the future. Moreover, on the basis of the collected data and 1415 text responses, we are able to identify the proponents and sceptics of these developments. We also determine the influential characteristics related to these developments and discuss power-related barriers to future developments. Thereby, our study provides guidance for policy-makers and civil servants. Moreover, we carry out the first comprehensive assessment of the future of public participation from the perspective of 171 elected representatives using a Delphi approach. The results obtained are not only of interest to German policy-makers; rather, they provide relevant information for all democratic countries with elements of public participation.