## Feature request #### Feature description <!-- Description in a few sentences what the feature consists of and what problem it will solve --> Currently, `spin_until_future_completes` only accepts a `std::shared_future`. It would make sense to accept both. See https://github.com/ros2/rclcpp/pull/971. #### Implementation considerations <!-- Relevant information on how the feature could be implemented and pros and cons of the different solutions --> Just templatize more the current functions/methods.