Carolina says hell no.

throw in a 1st round pick then, Do they say no to that? I highly doubt it.

Polak at 3.1 for 3 years.? No wonder why Hawks are in cap hell.

what would you sign him for?

wouldn't he's awful

So an aging overpaid Seabrook for Hanifin, And Ron Francis does this why.

They do.

the amount of picks hes getting in return

They still say no cause Hanifin is a very good defenseman and only 20. They don't need to take on an aging defenseman even if it includes picks. They want to finish the rebuild not extend it. They don't need picks.

It's all a nice thought.
Once one thinks of trading Seabrook, it's clearly a step into fantasy land so the Blackhawks might as well get Hanifin in return.
In reality, Seabrook's contract is not tradeable. If Seabrook were to become a free agent, would he get 6.8M/yr? Maybe, maybe not (I'd say no, but looking at the 2016 contracts handed out, he probably would), but for argument's sake let's say he would. Why would a GM trade for that contract/value when they could sign a free agent for that contract/value? They wouldn't trade for the value unless they want to be fired within a few years.
I get experience/cups matter (especially at the trade deadline w/an expiring contract), but typicallly not in an offseason trade of a long term contract.