I think FE Heroes' story will be the baseline for warriors' story.

[BalancedPro]

Two OC armies summoning warriors to fight for their Kingdom. I can even see them using the same OC characters from Heroes.

[Thany]

i dout they will use the heroes ocs since that game really recently came out, but i could see their own ocs for making the armies fight.

[Deva Ashera]

I see either Tecmo Koei working with Intelligent Systems to create their own original character(s) for the 'main' or just starting with a random Fire Emblem Lord (such as Chrom) and then having a new original Villain for the various heroes to fight against, perhaps one that like Cia in Hyrule Warriors, recruits various villains from past Fire Emblem titles.

If I had to guess though, I'd say the latter since I think Tecmo Koei would want to use a recognizable face for their main character like they had with their new version of Link in Hyrule Warriors or their various other spin-offs, such as Dynasty Warriors: Gundam, which seemed to use Hiro from Gundam Wing as the 'face' for the game.

Edited February 5, 2017 by Deva Ashera

[Ivy Wife Supremacy]

I'm 100% positive there will be at least 2 OC playable Lords like Sharena and Alfonse as the obvious main focus for starting the plot and of course the other FE Lords/Major Characters coming into play after.

[Etrurian emperor]

I imagine the story will be closer to that of Warrior Orochi. A big evil fuses all the worlds, the villains join him and the heroes must team up to stop him. 

I could also see some of the heroes joining the villain due to brainwashing, hostage situations and threats. 

[Thany]

3 minutes ago, Etrurian emperor said:

I imagine the story will be closer to that of Warrior Orochi. A big evil fuses all the worlds, the villains join him and the heroes must team up to stop him. 

I could also see some of the heroes joining the villain due to brainwashing, hostage situations and threats. 

and if you go that path, there could be 4 seprate stories to choose from, like how wu and shu and all that jaz had their own story arcs, we could have things like telius and elibe for different story perspectives. i look forward to how the story could unravel.

[LucarioGamer812]

I could possibly see heroes being a baseline for this but most likely they'll do new OC's. Unless they have the heroes cast function like how Lana did in Hyrule Warriors and be a ally that has a connection to the main villain. Then Chrom would be the figurehead like Link did.

[Folt]

I think we'd get a story that would be more similiar to the one in Hyrule Warriors instead: Chrom fights a villain who eventually gets other worlds involved and heroes and villains team up with one another but with Chrom as the main hero.

I mean, discounting the original incarnations of Zelda main series characters (Link, Zelda, Ganondorf, Impa, and Sheik), one OC was added as the villain of the game (and conveniently someone used by Ganondorf as a puppet, like in some of the main Zelda games), another is a good guy with ties to that villain.

Two are villains that give the OC main villain a trio and commanders under her to use before the rips in time and space thing (and also functions as OCs based on recurring Zelda enemies i.e. Volga is explicitly designed to make people think "Volvagia" and otherwise has a moveset that'd be kind of like if a Lizalfos/Dinolfos OC were a thing whereas Wizzro is obviously based on the iconic Wizrobe enemy which tend to be some of the hardest enemies to defeat + both are stereotypical villain clichés like the incredibly strong warrior who is incredibly hard to defeat and the disloyal cowardly backstabber who isn't as smart or as good as he thinks he is).

They also serve to make a group that foils the other main villain group: Cia, for all her power after the corruption, and initially appearing to hold her own against Ganondorf when he tries to betray her, proves in no uncertain terms that Ganondorf would ultimately win in a real battle between the two; For one, he's in a weakened state, and two, he's still formidable enough to battle her on equal ground (which ensures that her forces are weakened and hastens her death as she starts to use her life force to try to stay in the game), after which Ganondorf, having regained his full strength, simply amasses a new army, takes back the Triforce of Power, beats the other two Triforce wielders into submission and gains control of the full Triforce like he intended to do. Zant and Wizzro are both psychopaths, share a fondness for using magic, and serve as the strategist to their respectable leader (Ganondorf for Zant, Cia for Wizzro), but of the two, Zant is a much more competent tactician (as an ally advising Ganondorf, and the player by extension, as well as his enemy appearances, he makes and executes some incredibly good plans, and gives advice that is incredibly helpful) and is a better fighter on the battlefield + Zant is better aware of his strength in comparison to his foes and thus won't hesitate to throw himself into the fray if necessary to bolster his troops, proving he's more of an asset than a liability when the stakes come down (which is ironic, since Zant was much closer to that of a boisterous weakling in Twilight Princess). Contrast Wizzro whose plans are a bit lacking in contrast and who tends to flee at the first opportunity when everything goes south for him, and lets the army stay leaderless behind.

Ghirahim and Volga meanwhile serve as their armies strongest warriors (and both of them take human forms despite their true forms being considerably inhuman). Both also really love battling, but Volga tends to go into battle even if it's not in the army's best interests (probably the best example comes in HW Legends's update of Cia's third scenario where Volga and his underlings will jump into battle against Zant's forces at the first opportunity given if Zant's army make a move on them, even if Cia tells them to stay back since she wants to persuade Zant) while Ghirahim is capable of sticking to an army's goal/plan/objective and will do actions that help further it if he must. Also, they're both pretty different when it comes to their fighting styles, even if both are moreso warriors than wielders of magic.

And of course, Cia had to rely on brainwashing to keep Volga and Wizzro in line (which still didn't make them 100% capable of following her orders to the letter and spirit). Zant and Ghirahim were 100% loyal to Ganondorf from the very beginning that they entered his service, and as a result worked much better as a team.

And the fifth one came in as a result of popularity and so that fans could have a "girl Link". (Though I've honestly found the finished version to have many more similiarities with Tingle than with Link.)

And I think Fire Emblem has enough characters going for them from the current games that are implied to be the focus of FE Warriors that there's little need for OCs. Maybe one or two.

Or maybe Awakening, Archanea, and Fates characters form five factions (Archanea, Awakening, Hoshido, Nohr, and Corrin's faction) and they end up fighting one another before teaming up to take down a villain (maybe Grima) who probably made them fight one another in the first place?