Yeah I wouldn't take that chance. If teams are unwilling to go above 2 years for Happ, then I don't see why they'd trade assets for him six months from now and be obligated to pay the 3rd year they didn't want to give him now.
The Jays got $65m of value out of a 3/36 free agent signing and turned that into six years of McKinney and four years of Drury. Not a fan of that trade, but ultimately that was a win. No sense trying to get more out of Happ when the window of contention isn't there anymore and he's more likely to decline this time around.