I think the request for 30 minutes is a major tell, its gonna be intense pressure on old Joe to hold it together, physically and mentally.
At the sham primary debates, he was able to hide behind the other liar candidates and let them do all the talking.
It wouldn’t surprise me if this is the only debate. If Biden does ok tonight his handlers will pull him out of the other debates to lessen the chance of a major gaffe/medical emergency.