It'd be trivial for a plugin author to implement that,
if MC allowed plugins to change Playback modes. Unfortunately, it doesn't, though.
It'd be really nice if more of MC's internals were exposed to plugins. Unfortunately, it's all too common for somebody to install a plugin that does something unexpected and then that person blames MC for that behavior. In the worst cases, those same people then post all sorts of negativity about JRiver and MC when the problem lay elsewhere all along. I sometimes wonder if that isn't part of the reason why the SDK doesn't get expanded more often than it does. That, and the umpteen bazillion feature requests that they receive on a daily basis.