Will PS Plus be required for PS4 regardless if I want to play online or not?

So I've just paid for my PS4 ready for release on Friday and one of the questions asked by the sales person was...

Sales person: "Do you have PS Plus?"

Me: "No"

Sales person: "Well we are offering *blah blah blah*.... It is recommended as you will need PS Plus."

So correct me if I am wrong, but as far as I am aware (from reading several trusted reports) I can still use play PS4 games offline. For example Battlefield 4 solo campaign will be playable, but if I then wanted to play multi player I would need to purchase a PS Plus subscription.

Or have I missed the press release where it has been confirmed I will need a PS Plus subscription whether or not I want to play online?

Thanks.