PS3 owners of TPA who get a PS4 are owed nothing, period. If you bought PHOF for PS2, were you automatically entitled to the same game on PS3? What makes this situation any different?
Yes, PS4 owners are owed nothing, agreed. There is a big difference with encrypted (DRM'ed) download-only software vs. that mad available on generic storage units. I can play my PS2 PHoF after my PS2 dies on modern PC hardware. With the PS3 download-only content that still remains to be seen.
Does that put an obligation on FarSight? No. But it does put a burden on us gamers what ballpark we are willing to accept to find ourselves in. Remember: we are not a bunch of little kids that are being told what we can or cannot do. We (are at least supposed to) have elected representatives that write/change laws according to our wishes. Allowing to break DRM to allow inter-operability is one of them.
For now, save all your receipts. You can still buy new, supported PS3 hardware, so there is no urgency. But 5 years from now, the situation might be different.