Saw this on SCUSA initially. Seems worth re-posting:

‏ @SimonBorg
Details MLS Commissioner reveals in Orlando: "They’re going to open up CenturyLink field, 66,000 seats for the Cascadia rivalry" @MLS

Retweeted by Major League Soccer

I'm guessing that this is true since MLS re-tweeted it. I doubt they'd have done that if it wasn't a done deal. Unless they've just turned their Twitter feed over to an intern who doesn't know what he's doing. Which does happen.