EA and BioWare have announced that Mass Effect: Andromeda won't have a Season Pass. Additionally, Mass Effect: Andromeda will be available to those who subscribe to EA Access on Xbox One or Origin Access on PC for a "limited time" before the general launch.
Whether or not there will be paid DLC for Mass Effect: Andromeda hasn't been stated by EA or BioWare yet. Although Mass Effect: Andromeda has been said to be a self-contained story and not the first entry in a new trilogy, it would be great to avoid the mess that is Mass Effect 1-3's DLC model. It continues to be an enormous frustration that the Mass Effect trilogy's DLC is never on sale and some of it is just unavailable depending on which platform you play on.
It's not known how long EA/Origin Access subscribers will get access to the game before launch. Previously, Battlefield 1 had a 10-hour demo on Access, so EA may go that route, or allow access to the full game early.
Mass Effect: Andromeda will release on PC, PlayStation 4, and Xbox One on March 21.