Nintendo should validate the Wii U and announce at least one or two strong first party 3DS games.
Sony should unveil more Vita games and remind people how strong the PS3 is in 2013. Maybe show off another exclusive, price drop, etc.
Microsoft needs to show the most for 2013 in general, considering their release schedule.
Both Sony & Microsoft have equal need to show off new hardware for different reasons though. Sony needs the PS4 out there so they don't have a year deficit on the competition again (one they overcame this generation by the skin of their teeth) and Microsoft wants to stay ahead of the curve as much as possible.
Sony should unveil more Vita games and remind people how strong the PS3 is in 2013. Maybe show off another exclusive, price drop, etc.
Microsoft needs to show the most for 2013 in general, considering their release schedule.
Both Sony & Microsoft have equal need to show off new hardware for different reasons though. Sony needs the PS4 out there so they don't have a year deficit on the competition again (one they overcame this generation by the skin of their teeth) and Microsoft wants to stay ahead of the curve as much as possible.