Here's a prediction. I haven't read it anywhere; I'm just making a guess on my own.
Next season, the Seahawks will face the Miami Dolphins in Sao Paulo, Brazil. Here's why:
The Miami Dolphins have been awarded the Brazilian market, so it only makes sense that they'll be involved in the first ever game to be held in the country which was announced a few weeks ago, and indeed, there's been some rumors circulating which mentions that possibility. However, it's unlikely that the league would force, or that the Fins would volunteer, a home game as next season, they have 8 home games and 9 away.
So, that leaves one of their opponents. It's unlikely that they'd force a team like the Bills and rob them of a home game against a divisional opponent, so they're most likely going to be looking for a non-conference opponent so as not to affect competitiveness. The Dolphins have 3 NFC road opponents next season, at Seattle, at LA Rams, and at an NFC North opponent.
That brings us to our Seahawks. We are one of the few teams to have never donated a home game to the international series while the Rams have already donated one, and we have 9 home games next season, one of which is against....you guessed it, the Miami Dolphins.
So there you have it. You heard it here first.