In Europe, on most European airlines, if you fly "business class" short haul it usually means an empty middle seat. (There is usually a tray table on that seat.)
United Airlines is going to try something similar. Later this year, on some of its new Airbus 321's, one row will be marketed with an empty middle seat. Of course, this will cost a little more but no word on how much that is.
Would you pay extra for an empty middle seat?
United Airlines' new upsell: Keeping other travelers out of the middle seat