Killzone Shadow Fall is a pretty good game. 8/10 or so IMO. Mercenary is the biggest technological achievement on a portable in at least a decade, and is actually a really good game. It is being overlooked because of user base on Vita. I like both of them more than 3, so personally I see Killzone as on an upswing. Just because KZ2 is the best in the series doesn't mean they should drop it. That's like saying MS should drop Halo because of Halo 3....Also, the Helghast are engaging and interesting enemies.

To play devils advocate, and I seriously am being honest here, it shouldn't be scrapped.....but dialed down. It should not be marketed as a AAA FPS.

To use Halo as an example, and only because it is my favorite sci-fi FPS, and not because its the rivals sci-fi FPS, there are clear differences why Killzone just falls flat. For one thing, the lore is sloppy at best. Most of the time, you fight for a a side that the players don't care about whether they win or lose, or the ideals they have. The Helghast by comparison are more interesting on a aesthetics and ideological standpoint......yet you are killing them most of the time. In Halo, Master Chief is different in appearance. Badass looking, different from the others, but still Human, fighting for a noble cause while still following orders.

In Halo, you fight for humanitys survival, and with Halo 4 going forward, humanity's rightful place in the galaxy. In Killzone......you fight a pointless human on mutated-human (?) conflict with snowballing petty squabbles being the main focus. Wheres Earth in all this? Just Vekta and Helghan? If this is a war.....gimme a REAL war, spanning dozens of star systems. Granted my knowledge of KZ lore is spotty at best, I may be wrong with specifics but Im sure my general point is coming across here.

The series just screams "COD with scifi". Now when I say that, I mean its like COD players, where they buy it for the multiplayer and ignore the bare-bones campaign.

I can't comment on MP, because that is KZ's strong suit as I am told, but as far as campaign/lore goes, it leaves a ton to be desired from a fellow sci-fi junkie. Bash Halo all you want, but they got the lore down to a T.

KZ sells well enough to warrant sequels, but it definitely shouldn't be AAA anymore, if reviews are anything to go by.

I don't think they necessarily need to move on. KZ: SF represents a new direction that they're taking with the franchise. The execution needs some work, but it's not a bad game by any means. I know people want this to be the "Halo-killer", but it doesn't need to be that to be a successful game. After all, how many FPS out there realistically can compete with Halo outside of 2 or 3? It's like trying to create a platformer to compete with Mario. If that is the goal, then just about every game has failed, even those that have sold and reviewed very well.

Killzone is more tactile and has more of a grunt feeling than cod or bf which is why loads of people like it - why would they give up on the top pre ordered exclusive title?

I think Shadow Fall is a great game, seems very fluid and I like the items.

AAA is just an indicator that it's a big-budget game.  Plenty of AAA games have gotten mediocre to bad reviews.  Games are labeled AAA months/years before they even come out.  

You are right in that executives don't care for lower then expected metas if the $$$ is coming in. That is where the OP doesn't realize. But the idea that the low scores should in theory force the dev to make a change. Hell, Id say go for a reboot and make the story worth telling. Because at this point that seems to be the main aspect holding the game back from consistent 90 meta scores.

So to meet both points half way, SOny should keep KZ going, but "give up" on the current lore and just start from scratch.

They just need to go full all out sci-fi with Killzone.

I like Killzone. They should do an invasion where the helghan have found aliens and the war really goes to outerspace.

Metacritic score is low because most of the reviewers are utter morons and reviewed this primarily multiplayer game on the basis of a single player campaign only. Interesting that they did not do the same for Battlefield or COD both of which have boring campaigns but were scored on the basis of a 'multiplayer' game. If you want to judge this game on metacritic score then no offence but your opinion does not count much as you have no idea how this game is until you have invested time in multiplayer.
I have earned over 250 challenges in multiplayer so far and spent upwards of 30 hours on the game already (I did not touch the campaign, don't care) and this game is fantastic. Also look at the user critics on Metacritic and Amazon and you see a much higher score. For all the guys saying they loved KZ2, the multiplayer in KZ:SF is actually much more similar to KZ2 then KZ3. It is a unique experience different from both COD and BF.
The Killzone franchise enjoys a small but loyal community which just increased in size with KZ:SF.
This means Killzone franchises appear within the top 5 FPS games in the industry.
It also means that as people burn out of COD there is a high chance of them starting to play Killzone
How is that a small achievement? They sell enough to make a profit anyway.

Shadowfall was a pretty big departure from KZ 1-3 IMO, at least if we're talking about the SP.  MP is more or less the same, which isn't a bad thing since that's KZ's bread and butter.