FloatingWaffles said:

I'm surprised they didn't try to get it out there in November though since I feel like most games will sell better during that time once the holiday sales start during Thanksgiving and people will be desperately hunting for Switches (like they have since it launched) and looking for games to bundle with it as a gift. 

This is just a rumor though, could still be october or november. 

Skyrim is out then it may be that they don't want Doom and Skyrim competiting against each other.