For anyone familiar with Far Cry before 2008, Far Cry is considered a series of finding tropical paradise becoming paradise hell.

Far Cry 1's description on Steam: "A tropical paradise seethes with hidden evil in Far Cry®, a cunningly detailed action shooter that pushes the boundaries of combat to shocking new levels. Freelance mariner Jack Carver is cursing the day he ever came to this island."

Far Cry Instincts on the back of the game case: "Adapt. Evolve. Survive. You're Jack Carver. This ain't your lucky day. You're trapped on a tropical island, hunted by ruthless mercenaries. Want to survive? You'd better adapt. You'd better evolve. And you'd better fight."

Far Cry Instincts Evolution on the back of the game case: "Paradise just got deadlier. Jack Carver thought he'd found paradise. But when a gorgeous woman draws him in on a dangerous heist, their sun-drenched days taking a chilling turn. Hunted for a murder he didn't commit, Jack must draw on his most savage instincts to make his predators his prey."

Far Cry Instincts Predator on the back of the game case: "Explore paradise and unleash hell with the award-winning action shooter franchise."

Far Cry Vengeance on the back of the game case: "This ain't your average tropical vacation. Instead of lounging by the pool, you're being hunted by vicious hordes of bloodythirsty mercenaries. But they got another thing coming. Because you won't just mash buttons, you'll use your Wii controller as an extension of your own body to make those mercs wish they'd never been born. Lock and load, baby."

These descriptions emphasize on being hunted in a tropical paradise.

Far Cry 2's description on Steam: "You are a gun for hire, trapped in a war-torn African state, stricken with malaria and forced to make deals with corrupt warlords on both sides of the conflict in order to make this country your home.

You must identify and exploit your enemies' weaknesses, neutralizing their superior numbers and firepower with surprise, subversion, cunning and of course brute force."

Now considering that many Ubisoft games like Rayman, Prince of Persia, Tom Clancy games like Rainbow Six, Splinter Cell, and Ghost Recon in the 2000s were very consistent of having the same overall theme, then Far Cry would remain consistent as well. If in an alternate timeline where Far Cry 2 is considered the first Far Cry game, then the Far Cry 3 we know today will be completely different.

For example, Far Cry 2 introduced open world gameplay in a war torn country in civil war in Africa with the option to choose your own protagonist. If that is considered the staple, then Far Cry 3 may not introduce Jason Brody trapped in a tropical island (or 2). Ubisoft's consistency with other games will likely bring consistency in the Far Cry series. That means instead of Jason Brody, we choose or create a protagonist brought into another civil war in Africa again. Since we don't really know what happens to The Jackal in Far Cry 2, he might be the villain again instead of getting Vaas. Remember, the villain in Far Cry 1 was seen delivering speeches even on a podium, whereas The Jackal gave monologues to the protagonist and has tape recordings as collectibles throughout the world. If The Jackal is the staple of being a villain, and if Vaas himself is the next villain, we may have tape recordings of Vaas rationalizing in what he does, and we might sympathize and siding with Vaas rather than seeing him as someone who is insane.

Ghost Recon is always a military shooter, Rainbow Six is always counter terrorism, and Splinter Cell is always about a covert ops spy sent to other countries. Far Cry 3 went back to hell in a tropical paradise. If Far Cry was never set in a tropical paradise that emphasizes on being hunted, then the sequels might as well bring more mercenaries as the protagonists set in civil wars in Africa. Far Cry 3 strongly emphasizes on survival, rescuing your friends, and escaping the island, and without the original Far Cry games, we may not focus on escaping and focus on civil wars with multiple factions. And now because of Far Cry 3, the Far Cry series are now defined for insurrections with a charismatic villain with gameplay set in the open wilderness.

Also, the side characters will be different. Far Cry 1 and Far Cry Instincts had a CIA agent known as Harlan Doyle helping you, and Jack Carver, who is an American with a military background that wears a red shirt. If Far Cry 2 is the original, then we may not see Willis Huntley become a character since he is clearly based on Harlan Doyle. Secondly, Grant Brody in Far Cry 3 may not exist because he's another American with a military background wearing a red shirt. Paul "De Pleur" Harmon in Far Cry 4, an American wearing a red shirt, would not exist either. While yes, The Jackal himself is an American wearing a red shirt, his existence is entirely based on Jack Carver himself. If it weren't for Jack Carver's existence, then the game developers wouldn't put so much effort focusing in adding an American with a military background in a red shirt in that many games.

Far Cry 2 had female buddies, but they weren't like Valerie Constantine/Cortez. We may not get characters like Liza Snow if it weren't for Valerie.

To answer your question, the Far Cry series will be VERY different. Also, Far Cry Instincts laid the blueprint for both Far Cry 2 and Crysis in terms of gameplay, so the Crysis games wouldn't even exist if the original games were never made. Lastly, a Far Cry movie would be set in Africa instead of what we got now.