I have the same concern. Want to buy for the PS3 now and maybe look for a PS4 much later on.
From the [url=https://support.us.playstation.com/app/answers/detail/a_id/5372]Playstation link[/url] (accessed 9/11/14 12:15pm US-Eastern time), bold emphasis is mine:
[quote]
Digital Upgrade Program
The PlayStation 3 to PlayStation 4 digital upgrade is now available.
When you buy/redeem the Destiny Digital Base Game, Digital Guardian Edition, or Expansion Pass for PlayStation 3 on or before January 15th, 2015, you can download the Playstation 4 version from the PlayStation Store for free. Your Sony Entertainment Network Account (PSN ID) will retain licenses for both consoles so you will be able to play both versions. Details on the upgrade program are located on the game's official website: DestinyTheGame.com/digital-upgrade.com.
How to upgrade the game
* Log into your PlayStation 4 using the same Sony Entertainment Network Account (PSN ID) used to buy/redeem the Destiny digital content on PlayStation 3.
* Navigate to the Destiny content page or search for the corresponding item you purchased previously on PlayStation 3.
* Add the item to your cart and complete the transaction.
* Wait for the download to complete.
How to upgrade the Expansion Pass (for owners of the Limited Edition and Ghost Edition)
* Log into your PlayStation 3 and redeem the voucher for the Destiny Expansion Pass in the PlayStation Store on or before January 15, 2015.
* Log into your PS4 [b]any time after[/b] using the same Sony Entertainment Network Account (PSN ID) used to redeem the Destiny Expansion Pass on PS3.
* Navigate to the Expansion Pass within the Destiny content page in the PlayStation Store.
* Add the item to your cart and complete the transaction.
* Wait for the download to complete.
[/quote]
So I think it's clear that you can get the Expansion pass on your PS4 really at any time, implying no expiration date. But they did not use similar language about the game itself, which is worrying.
Side question: would a digital download purchased from Gamestop and redeemed on PS3 qualify for this deal?
English
-
For a point of comparison, when the offer went live in the Xbox 360 store the wording is: [quote]Offer expires 1/15/15[/quote] Once again it does not clarify if you purchase before that date if you also need to upgrade before that date, but considering the offer will expire I wouldn't be surprised if you had to upgrade as well.