Just some thoughts on what a sort of successor could be.
TF3 imo will look more like the large scale Battlefield type games. Lotsa players, combined arms, etc. There's also a good number of NPCs to make up the slack I guess.
Players can choose to play as a Pilot, a Spectre, or a Grunt.
Grunts players serve as a squad lead of six NPCs. Spectres a unit of four.
Grunts/Spectres can use conventional vehicles, Pilots can do that but also Titans.
Tanks, helis, jets, light utility vehicles... They all have a place.
Jets fight air units, can harass ground. Helis murder tanks, and can threaten titans.
Light armour can do a lot of stuff, but also carries people around.
Titans are good at everything, but not the best.
Infantry is the heart and soul of Titanfall.
So what can you do?
Well, you've got your primary, and your sidearm, grenades, body armour, abilities, jumpkit...
Primaries can be customized more deeply, with magazine, rail, underbarrel, barrel, optic... Same for secondaries.
Armour plays a significant part in the game. What you wear makes explosives, bullets, less deadly or more deadly.
Jumpkits can be modified for different playstyles. Welcome to being an elite operative.
And so forth. Of course, Spectres and Grunts don't get fancy pilot stuff, but you can customize the loadouts of your unit.
Of these, Grunts are the bread and butter. They can ambush armour, attack an objective, hold a choke... they're lightly armoured and moderately quick, but they have numbers and a good player can massacre enemies with their fireteam.
Spectres are the heaviest. They sport thick body armour and heavier weapons. But... they're slower, and less numerous. Also, they're electronic. Expect Data Knifing.
Pilots are high speed, low drag, and absolutely lethal. With access to the widest armoury and Titans, they can change the game fairly easily, but their stamina is poor, with lower ammo reserves for their guns, and a fairly lengthy cooldown between Titans.
