Fairly certain we won't see a Seattle bid until the NJ Super Bowl is in the books and the owners get a chance to discuss how it went. Paul Allen isn't the kind of guy to push something like this without some consensus first... but conversely if the owners and attendees end up liking the NJ Super Bowl, you never know.
(That said I participate in an event annually that is usually in New Orleans. We did it in Boston this year, and there was a LOT of complaining... and some regulars didn't come because of it. It's totally silly but people do get used to certain things, and if they want a location that's going to be warm outside, or a dome, or both, it's very hard to get them to accept an outdoor venue with cool or cold temperatures.)