I am just wondering if there are 2 licenses required to play on both ps4 and PC. They said you have to have both copies to be able to install on both platforms which makes perfect since, but will the licenses be required for both as well.

Heavensward must be installed on the client to access the areas that will be added in Heavensward. If you are planning to log back in on a client that doesn't have Heavensward installed, make sure to log out in an FFXIV: ARR area.
My wife and I are always switching between PS4 and PC so I don't want to have to purchase 4 copies of the expansion each time. I will purchase one physical PC copy and one physical PS4 copy and hope that they are just talking about installs and that there isn't actual different key codes for the different clients like we had for the main FFXIV: ARR game. If I am wrong, then oh well and I will just suck it up.

EDIT:
Quote Originally Posted by Eidolon View Post
Heavensward must be installed on the client to access the areas that will be added in Heavensward. If you are planning to log back in on a client that doesn't have Heavensward installed, make sure to log out in an FFXIV: ARR area.

This interests me most. It doesn't say you necessarily have to have BOUGHT it, just that you need to have it installed.

This mgiht be where torrents or friends with the other version of the game come in handy. I'll bet that you can buy the PS4 version, and just install the PC version and your Service Account should have access to all the patch areas. (Basically using the code from the PS4 version to make yours a 'Blue skies of Ishgard' account.)
I see we had similar thoughts.