Yes, it is an online game. No, it is not an MMO game. Neither is Destiny.
...and are you serious about the subs suggestion/speculation? Oh wow. There will probably be some sort of microtransactions in the game, but I seriously doubt that there's even a chance it'll have subscriptions. That's what Xbox Live Gold is for anyways.
The game has you playing with and against other online players? Just like division, and other online focused games.
Looking at it, I can guarantee there will be cosmetic microtransactions or separate dlc to customize your pirate and ship.
I guarantee there is a level system or rank system on how your ranked among pirates. I also guarantee there will be something along the lines for late adopters, IE you can buy experience through in game currency through the store.
They did it with Forza, they tried having F2P fable with microtransactions, the req system in Halo 5 is similar to a microtransaction system.
They have been doing it, don't be naive.
Do I have to repeat my first comment again
Are you exclusively revealing that Sea of Thieves is an MMO with a monthly sub and whoring it out with micro transactions lol.
I am saying it's not far fetched seeing they've added micro-transactions in Halo 5 with Req system, in Forza, tried to make fable into a gigantic, dota inspired game with bought character,s and probably loot packs.
It's not rocket science to understand what Sea of thieves is about, and how they would try those types of things for the game to continue as a service since it's primarily online. You more than likely have a rank of your pirate or sailor type character, probably can improve to become captain and have your own custom ship.
So if those are like my educated hunch telling me in the game in some form, you can expect there to be ways to pay your way to first mate or captain if your a late to the game.
And there will be custom outfits and such which you probably can buy with in game loot, or buy them with real money in some form or fashion.
The game is online only from the looks of it, to keep supporting the game, how do you expect them to do that if this is in fact how the game plays out?
Because seeing how MS went ahead and green lit fable legends which was a F2P game you knew they were trying new paywall types to see what they could get away with. Hell it's currently in Halo 5, forza.
So yea, I'm making a educated guess, about a online game that has you looting and plundering against other players.