In an interview i saw with one of the devs.....he was standing by a tv sreen with the title menu behind him, & blacked out at the bottom was "download content".
Why would that be there if they were'nt going to do DLC?
I'm willing to bet my house that they will do download content....& it would'nt suprise me if they have ideas for it already.
It will make them more money,allow them to implement new ideas ( or fit ideas in there ,that they did'nt have time for etc ) , & they know people will buy it.
Just my opinion

As for a delay on PS3 who knows...we'll just have to wait & see.