Any trade conversation would likely involve info on his demands, and if it got to the point of being close probably talks with Trouba's agent (like what happened with Andersen). IMO, the only deal that makes some sense between TOR+WPG would be Gardiner + and wouldn't involve Nylander or Petan. Gardiner has a lower ceiling, but contract status is in his favour. I can't see a deal going down if the only way to sign him was 7x7, but no one outside of those negotiating knows what his actual ask is.
WPG probably wants to keep him but isn't ready to commit long term yet (not based on anything though). Far too much risk at 7x7, but if was 5 or 5.5 x 6yrs like Rielly/Jones I'd be down.
There has been zero real feedback on Trouba's contract demands, nothing to date but false rumours. His agent has publically stated that Trouba is absolutely not asking for 7 mil per year, he's clearly asking for 6 something per year, team will be offering likely 5 something per year. Let's see where the settle. Trouba has stated he wants a long term deal, no bridge deals.
If Chevy ever did decide to trade Trouba (highly unlikely but possible) he would likely target:
1) Equally young, proven LHD with same high end potential. Very rare
2) Near NHL ready elite LHD prospect that's a sure thing.
3) Very high end centre, young with huge potential.
4) BPA (including wingers)