Your probably right with Gaikai, that may be Sonys answer. Hopefully everything works out when they finally release it. 

Then explain why, when your copy of ___ is available on the PS4, you can't simply download it? It makes NO sense. If your purchases are saved in your PSN history (they are), then when they become available on the PS4 store, then why can't Sony let you download them for free?

For Sony's sake, I hope they find a solution for this hiccup.

Because the PS3 is different than the PS4.  Just because the system is made by Sony doesn't mean it will magically play on any Sony system.  It's no different than trying to run a digital X-Box 360 game on the PS4.  Different console, different architecture= you can't play it.

IF Sony starts offering PS3 games on the PS4 to download, then and only then will you have a point.  But, right now Sony hasn't really detailed their plans for this.  Keep in mind though, that Sony is under no obligation to allow you to transfer PS3 games to your PS4.  Sony never promised that you'd be able to use PS3 games (digital or otherwise) on future consoles.  You'll still have your PS3 to play PS3 games.  Backwards compatibility would be a nice feature, but Sony is not obligated to offer it.

We all KNOW that most, if not all, of the content available on the PSN store will be there on the PS4. That's what I'm saying. IF the same games we all bought on the PSN store for PS3 are there to download for PS4? Then what excuses will they have then? Because at that point, there IS no excuse...other than "hey, we don't want to". lol

what you just said has absolutely nothing to do with PSN. PSN is account bound and any PSN game is playable on mutiple machines if the machine is capable of running it.

Did Sony say something about that, or is that just your assumption?

Size will not matter, but you bring up a good issue. Any game that has a Vita version should easily have a PS4 version. So I expect games like Sound Shapes, Retro City Rampage, and any other cross-buy/play title should easily be able to upscale and operate on PS4. I kind of hope you can use remote play to play Vita games on PS4 anyway, but this would be some relief to those who don't own a Vita to have access to those games. Just an idea though.

Perhaps you are missing the reasonings many have already listed in this thread. The different architecture in the PS3 makes all PS3 games incompatible with PS4. This includes titles that are digtal only. In order to have them on the PS4 every individual publisher would need to be contacted for approval, maybe funding, the original developers would need to port it or hand over assets for another set of devs to port. This would cost millions, takes months away from devs, and might result in shoddy ports. The costs might be so high that they might attempt to charge a small fee to previous owners ala Nintendo Wii U style. It just isn't worth it. Now there might be some PSN games available thanks to non-PS3 version assets existing if they can get hold of 360, PC, or Vita code.

As for going on the PS Store on the PS4, it will probably not display PS3 store content. Vita's PS store is a good example. It only shows content that works on the system. While you can browse through your download list and see PS3 games, it will prompt you that it can not be downloaded on that system. If you want to play PS3 games, play them on a PS3. Lack of backwards compatibility for these titles is the trade off for switching to x86 architecture, which its benefits far outweigh that.

Put your PS3 copy in and then stream it from Gaikai?