Evil Within and Shadow of Mordor are my two go to games right now. When I get tired of them, I'll play some Forza Horizon 2. I do go back to Destiny every now and then but I hit level 26 and just sort of stalled. I'll revisit for sure when the DLC comes out. I love Destiny, but the content is just lacking right now.
How would they even do the upgrade discount if you bought it physically? Would it just be the Online Pass that unlocks it?
I'm guessing they would do it like they did with Battlefield 4 and Assassin's Creed 4, you use your PS3 disc to launch a downloaded copy on the PS4 system you purchased for X dollars. You would need your PS3 disc to play the game - that's how I play Battlefield and AC4 on the PS4.
Get the fire longsword early since that will scale with what you're doing.
I actually am going INT/STR so I used a bonfire ascetic on Duke's Dear Freja to get the Moonlight Greatsword which scales with Int. I also got the Blue Flame sword which acts as both a sword and a catalyst/wand to cast spells (you cast spells with R2.) The Blue Flame will drop from an NPC invader on your way to the NG+ version (or using bonfire ascetic on the bonfire before the boss) of DdF.