All Sony would have to do is show the more powerful games during their presentation. I think Destiny is being made w/ exclusive content for the ps4, show that and you may have a shot. Valve is already super friendly with Sony as well, so are indie developers outside of Behemoth and Ska Studios who still ride Microsoft's dick.
What I CAN see is Microsoft showcasing a lot of EA games during their presentation since EA is betting all of its chickens on Microsoft. If the Witcher 3 has any appearance in here as well I could see them showing up for the PS4 since they're pretty big on anti-DRM thoughts.
If I were Sony and Microsoft pulled this and a lot of studios took the bait, I would just release press releases to the press, or ad campaigns, showcasing how all of those games are also on PS4.