They have already confirmed the remaining 2 debates.Not sure there will be a next debate. I wouldn't be surprised if Biden's team puts out a statement similar to the following (not that I agree with it):
"Last night all of America witnessed how President Trump spoke over and insulted the former VP incessantly. Due to the environment that President Trump brings to the table we find any further debates a total waste of the taxpayers time and money. Therefore, we will not be taking part in any further debates involving Donald Trump. We instead will work hard fighting for the American people with our ideas and policies and work towards bringing unity and prosperity to the country."
Basically he will try and play off of this to bow out and count his blessings he didn't totally fall apart last night.