Who will we dump

I don’t think they does this. They would need a first

Maybe a first, and no retention for 3 years. But they just traded for him and he's been good so wouldn't make much sense

Seattle probably wouldn't take that much of a downgrade to their wing for a 2nd and a 3rd. Bjorkstrand is a very valuable top 9 winger to Seattle right now and is an important part of one of the best 3rd lines in the league right now, and they aren't in desperate need of picks any time soon with their incredibly fleshed out prospect pool despite only existing for 3 drafts to this point. It's definitely not like Seattle wouldn't take a cap dump, but they'll definitely want to force a massive overpay of assets.

Probably a guy like Iorio and a mid round pick along side Mantha might still too little for Bjorkstrand (not because the value isn't there, but because the caps have no leverage)

I don't think there's a chance Seattle considers this. The Kraken traded for Bjorkstrand just last year with an eye towards keeping him around for the long haul, so they aren't going to turn around and ship him out after just a year. A pair of third rounders isn't nearly enough of an incentive to make a major downgrade at winger while also retaining $1M in salary for three seasons anyway.