I don't know if games like Killzone 2 will in fact make 3rd party developers try harder or not. Don't forget that Guerilla have had an unprecedented amount of time and cash to make Killzone 2 how it looks today. 3rd party developers don't have the money or time to put the same level into their games.
What we should expect over the course of the next few years is for those developers to create their own PS3-specific engines that utilise the SPU's more hence making the games identical on both the 360 and PS3.
One other longterm problem is this! It's pretty obvious that so far, the PS3 is showing it can do more on-screen than the 360 and over the next year or two, 1st party games for the PS3 will look better than 3rd party games and 1st party games for the 360 (unless 360 developers somehow manage to get a huge increase in performance from their engines that they've not previously had). So technically, the PS3, through it's 1st party titles will move ahead of the 360 and will infact leave a fair number of the 3rd party titles behind.
Will PS3 owners start ignoring standard run of the mill 3rd party games while the 1st party are so much better and will 360 owners start moving towards the PS3?
Prediction (June 12th 2017)
Permanent pricedrop for both PS4 Slim and PS4 Pro in October.
PS4 Slim $249 (October 2017)
PS4 Pro $349 (October 2017)
