So apparently it's going to be a full priced game and launching with only 3 maps at launch...
the other 2 maps better be WAY more complex than the first one they showed, because if not the game will be super stale really fast.
the map design shown in their playstest recordings is super basic and would fit more in a battle royale kinda title where dynamic team fights are the focus.
an extraction shooter however lives and dies with gameplay variety. if you spawn into a map, and you move along a specific path, the way you walk down that path better be as full of variety as possible.
in this type of game you will eventually go similar paths through the map dozens of times during your playtime with the game. if that path only has a few simple walls, a few simple 2/3 room buildings and maybe a few trees, eventually every time you go down it will feel identical
games like tarkov get around this due to the sheer complexity of its maps. it has urban buildings with dozens of apartments that each on their own have multiple rooms. you can go through windows, up on roofs, through broken walls, all interconnected and interwoven into eachother.
there's a map with a gigantic mall, that's just as complex as you'd imagine a mall to be. shops with back rooms, escalators, multiple levels, underground levels etc.
meanwhile that map of Marathon they are currently showing looks less complex than E District in Apex Legends, and significantly less complex than Verdansk in CoD Warzone, both of which are battle royales where map complexity is less important.
on top of that many other things seem very streamlined in terms of missions and the loot system. and I'm not sure if that's something an extraction shooter is supposed to be.
Tarkov is the extraction shooter king still, and it has its hardcore playerbase because it's the opposite of streamlined.
if you streamline stuff you take away part of the learning curve, and that learning curve can be something that keeps people playing.
so I think the biggest issue to overcome for Marathon will be longterm engagement.
if they streamline the game too much, people might be losing interest really quickly as they will have seen everything there is to see, and can't really learn anything new or experience anything interesting.