Tbf, both Forza franchises have always been handled by 2 entirely different studios. So Sony would have to purchase or create another studio that is dedicated to a second racing IP. 

Would be pretty awesome if it was Motorstorm. I only ever played the first game, but I firmly believe that game was the blueprint used in making Forza Horizon. They're pretty similar IPs focusing on off-roading and a fictional festival. 

Started playing Just Cause 4 for the first time in nearly 4 years (haven't even halfway completed the story) and I find myself liking it again. I love 2 and 3 but never played the first and 4 had trouble gripping me.
Will I enjoy it enough to beat the story? We'll see.
I do think 5 or a remake of 2 are inevitable on PS5/Series/PC.

What games do Just Cause play like that? I have the games but never played them.

Remake all 5 games. Start with the first, give it a better story mode. Then just add content from the remaining games like a live service or something. 

No need to create a new game. 

I did a quick search about the rumored game and I found this:

-The game has been in development for some time.
-They teased the possibility of showing their project last year but it didn't happen.
-In job descriptions they have called the game a bran new game.
-This is included in this (https://startup.jobs/senior-animator-rigger-stellar-entertainment-3961673) job description from last year, "Setup and maintain animator friendly rigs for different types of vehicles and characters (mostly creatures but some humanoid)."

So ... sadly it doesn't sound like is Motorstorm but it kind of sounds like a karting game and I think PS actually needs a supreme karting game, this could still be cool.

Just Cause are big open world games before it became a common trend. 4 is the worst reviewed one, but I haven't played myself. 3 is ok at best with bad mission design. The series peaked at 2. Not sure the novelty of them holds up as much as back in the day. Just being these huge open worlds you grapple hook anything, even a helicopter mid air after jumping out and just fuck around and blow shit up. Still fun but not the mind-blowing games they were back in the day. A lot of open world games with as much and more freedom since. The story and characters are fighting dictators. I found 3 to be really buggy. Little in the way of game breaking but driving a truck and the truck pops out of thin air. I was standing in a street then suddenly trapped inside an ambulance. A lot of weird shit like that.

So its like Red Faction Guerrilla (at least from the way you explained it, the closest thing I can think of)?

Eh JC is just JC.  You won't be destroying everything you see. Most things are not destructible. Just vehicles and objective areas, like a site full of giant gas tanks. It's not physics-based like Red Faction. There is physics to the grappling or attaching rockets to a cows ass (or people) and watch it fly for giggles if you want.

Soon as I'm done with Clair Obscur I think it's time to return to the pods.

Dunno where it comes from but saw people talking about Horizon 3 coming in 2027, which I can indeed see, both because it was the time that took from 1 to 2, and that it will turn 10 that year... but the rumor was also saying it would be a PS6 launch title, which makes me pretty much guarantee it is completely fake.

PS6 won't be coming in 2027 and Sony will not hold a game like Horizon for a new console release, as they never did anything like that, and proved every time they release their biggest games always whenever they are done.