The owner of kbin.social (and creator of kbin incidentally) has been MIA for a few months now, so it's presumed that it's over. I haven't heard of anything concrete regarding the fate of kbin.social or ernest though - unless someone has heard differently, it remains possible that ernest returns in a year or two and brings kbin.social back up.
I think https://kbin.earth/ exists as an instance still running ernest's original flavour of kbin (as opposed to its sucessor mbin).