But that's just it, they are struggling to replicate the quality of ANY of those three games.

No,
Letting go of Killzone would mean losing the market share in the FPS genre that Killzone has gained through the last 2 iterations selling around 2 million plus. Obviously the quality of the game is dipping through every new Killzone game, though as long as the sales stay consistent around that 2 million Mark and Sony is able to keep the game profitable no issue.

If Killzone SF sales around 2+ and is profitable keep it, if not toss it out the door.

I am very disappointed about the newest iteration of Killzone of won't be buying it until bargain bin cheap. Though letting it go would be losing 10 years of work.

To me so long as the games are profitable then they should continue to make them. I've enjoyed KZ2/3 and am looking forward to KZ:SF, but I don't see why a game needs to either sell Halo numbers or go home.

Personally I'd love to see Guerilla games morph KZ into a Mass Effect type game rather than just a plain shooter, I think the KZ universe has enough potential to pull it off.

well they will make that choice based on the sales..so it's too early to tell

But GG is working on a new IP. SSM is working on 1-2 new IPs and so on. So I think we will see more and more new IPs from Sony in the coming year being announced

Sony should license Epic to make Unreal Tournament and exclusive FPS for the PS4.

I think the issue is more with GG itself. They have a lot of talent, but they're just missing a major something with every game they make. What I think they really need is a few developers with talent in story-telling and character development on the level of Naughty Dog plus 2-3 major developers from infinity ward to refine their gameplay.

If they had these 2 things, I really believe their games would go from okay/mediocre to great or even amazing. Sony needs to see that GG is not a failed developer; they simply have some holes that need filled.

When you say "compete with Halo," do you mean critically or commercially?

I haven't played Shadow Fall yet but when I get PS4 I plan on getting it because the multiplayer looks and sounds good. Im not sure what was so bad about the story but I didnt care for the story in the franchise anyways. I just get them for the multiplayer and it is probably one of the best multiplayer shooters out there.

Loved KZ2, Liked KZ3, Loved KZ:M, havent tried KZ:SF. I dont think they should drop the franchise but they have to pick up their game to appeal to a larger audience.

I love Killzone, so it's a no for me. I don't care about review scores or sales. I'm just having fun. After all, Sony also does things like The Last Guardian or that Quantic Dream stuff. Games that won't sell that much anyway. That's one of the things I really like about Sony, tbh. They don't just do endless sequels of games that are guaranteed to sell like EA and Activision. They also bring games for niche audiences.

Now, Killzone isn't so much niche, but whatever, I want it to stay. It's my favourite shooter by far. I don't want to ever mess with Bugfield again, where you have to pay the price of two games to get the full experience (premium). And I don't like CoD since the second part. The first one was a blast, but after that, it got pretty boring imo.

I'm gonna play a little Killzone: Mercenary now. Almost got that platinum...