I really think that a large part of the Destiny fanboys are gonna at least check Marathon out.
I've been hanging out in the discord server and its busy with over 65k members.
Not that 65k is gonna be enough to push the game into playability, but there seems to be enough buzz over "new thing from Bungie" that it's caught the attention of the normies.
Also, the devs on the discord server have been surprisingly laid back. There has been a "meme" of people reacting with the pregnant male emoji
Some of the people in the server are getting really upset about it and crying to the devs/mods. To which they respond:
Pretty funny shit watching them sperg tbh