You cannot play PlayStation 4 games on a PlayStation 3 as the disks and disk readers are different meaning that their readers cannot read the disks properly.
unfortunately you cant put PlayStation 3 game straight into a PlayStation 4, but fortunately there are a select few games on the PlayStation Store that are backwards compatible, such as Grand Theft Auto : San Andrea's and many Batman game. But for the most you will have to search the PlayStation store yourself to see what games are backwards compatible.
No and neither console plays the others games
In short, no. Sony haven't released any information regarding a PS4 yet, so we can only assume that you cannot. It is highly likely you will be able to play PS3 games on it, that is - if it really comes out.
You should wait for the PS4 to exist and have games before you want an answer to such a what if question. Based on the past when a new console is released the old one can not play the new console games. Why would you buy the new console if the old one could play the games.
No you will not be able to play the games either way. Systems changes on the PS4 allow them more design capability for games and many titles will be released in a downgraded PS3 version. You still will have to have a PS4 to play PS4 games and a PS3 to play PS3 games.
No, there is no plan for PlayStation to stop making PS3 games. The company recently released the PS4 console. PS3 games do not work in the PS4.
No, the PS4 does not have backward capability and cannot activate (play) PS3 or PS2 games.
You will be able to play it on both the PS3 and PS4 gaming consoles. The beauty of Playstation is that you can access their games and titles via consoles, along with wireless and remote devices.
No it will not
No, the PS4 will only run the games made for the system. But there is a application on PS4 called PlayStation Now which will allow you to play PS3/PS2 games for a price.
You can get a PS3 and the PS4 is not an actual product. If you want a console buy a PS3 because the PS4 can not even be preordered it's release is so far in the future
No
yes!