Do you think it will happen?

Exhibit A:

Epic Games owns the Gears IP and "can do what we want with it"

http://www.vg247.com/2010/03/15/rein-epic-owns-gears-ip-can-do-what-we-want-with-it/

So what if Epic decides they want to go multiplatform, get more sales, and sign a deal with EA or Activision (like Bungie did). The difference with Bungie and Epic is that Bungie does not own the Halo IP, Microsoft does. Epic, however, owns Gears of War IP and can do whatever they want with it. Yes, that means they can put it on PS4 if they want to. 

Exhibit B:

Epic Games would love Gears on Playstation. 

http://www.1up.com/news/gears-of-war-ps3-epic-love

Exhibit C:

Look no further than Call of Duty, Uncharted, Battlefield. Shooters sell very well on PS3 now too. COD sells over 10 million copies on PS3 every year despite 360 having timed-exclusive DLC. Some games like FFXIII, Batman:Arkham Asylum, Resident Evil 5, FIFA, and others actually sell better on PS3 than they do on 360. 

Now Gears of War games usually sell roughly 6-7 million copies on 360. They would probably sell an extra 6-7 million on PlayStation systems. 

How could Epic possibly turn down an extra 6-7 million sales? People will say it's because Microsoft is money hatting them. But how much could MS really be putting forward for this one IP that they don't even own? Developers apparently make $10 from every game sold at $60. They also lose out on all the DLC Map Packs that could be sold to PlayStation gamers.

Do the math. Epic is missing out on 60-70+ Million dollars every time they release a Gears game without putting it on PlayStation. Microsoft might pay for some development and marketing, but there is no way Microsoft is paying Epic $60+million every time a Gears game is released. 

From a financial standpoint, Epic would be downright silly if they don't put Gears of War on PlayStation 4. 

Exhibit D:

Epic and Microsoft had made a deal for the first 2 Gears games to be exclusive on 360. But that was a very, very long time ago. PS3 wasnt even in stores at the time. Epic was not nearly as big as they are now. Gears was a new, unknown IP. Now Epic is one of the leading industry developers, and Gears is a well known IP. They don't need MS to market it for them anymore since Gears is a proven commodity, and they dont need MS to help with development costs since theyve grown so much.

It's also important to note that Epic and many other PC devs like Valve were very disappointed with the PS3's technical architecture. PS3 was harder to develop for. It was harder to port games to. 

We all know this will NOT be the case with PS4 when it is released. Infact, PS4 will probably be the BETTER system to port to, and it will most likely be more powerful than the next Xbox. Devs were happy when Sony announced PS4 would have GDDR5 8GB RAM. PS4's specs were made "by developers, FOR developers". We even saw Epic's Unreal Engine 4 at the Sony meeting this past week, and Sony's 1st party game "Knack" is being made with UE4. Needless to say, Sony has reached out to developers and has done a great job getting their input on the new console. Oh... did I mention Xbox fanboy Cliff Bleszinski is no longer at Epic?  

Simpy put.... Times have changed! It isn't 2006 anymore. 

Conclusion:

Epic owns the Gears IP. Epic wants Gears on PlayStation. Fans want Gears on PlayStation. Sony wants Gears on PlayStation. EA/Activision would love to publish Gears on Playstation. There are absolutely no technical limitations that would prevent Epic from putting Gears on PS4.

There will be NOTHING holding them back this time.

I think there's a 50/50 chance Gears of War franchise will be on PS4 next-gen. Epic's co-founder Mark Rein seems happy with the Official PS4 specs. Now let's hope Epic puts those specs to good use. 

For all PlayStation fans that would like Gears of War on PlayStation 4, you can contact Epic through their Twitter accounts and tell them you want Gears on PS4

https://twitter.com/MarkRein 

https://twitter.com/epicactual

https://twitter.com/EpicGames

I actually fully expect Gears to go multi plat next generation

I agree with everything in your post except one thing there is no way in in hell Gears would sell the same amount on PS4. That's like Final Fantasy or Metal Gear selling the same amount on 360, as it's seen as more of a Xbox franchise.

If Gears went over then I would have 0 reason to even think about an Xbox. It was the only series that interested me on the system, but not enough to get me to purchase. The outrage would be HUGE if it did happen, however.

i'm not going to twitter. i am vgc'z number1 Sony GEARS-Head. you make great points, and i hope gears does come to PS4.

GEARS judgement doesn't look like something i'd want to play, and if anyone were to publish GEARS, it would bee EA.

same here.

There is definitely a chance. I really can't think of a single good reason why Epic wouldn't go multi-platform with Gears. It would literally be throwing away millions of dollars.

Even if Gears doesn't come, I'm almost certain Epic is developing something else that will be multi-platform.

However, I also expect Microsoft to ready with a new IP of their own next gen to counter-balance that. If they don't, then they deserve to take a hit.

Thats a bad comparison on your part.

FFXIII sold way less on 360 because it was still exclusive to PS3 in Japan, which is a huge territory for FF games. 

Well that would be interesting if it happened, I have no interest in Gears of War. I tried to get into it, but I just couldn't.

It's certainly very plausible we will see Gears on the PS4 (and perhaps PS3, depending on the time frame during which the game goes multiplat), however, Epic would need to consider a few factors before going forward with it.
For starters, The game would obviously sell considerably less on a PlayStation console since the series and it's following have always lived by the Xbox. Epic would need to consider whether losing the likely large amount of money MS provide Epic for marketing etc would be recuperate by the PS's release.

Looking at the numbers for how it went with Mass Effect (though of course ME was never a true xbox series with all games appearing on the PC) I'd say in all likeliness, it would be well worth Epic's time.