There are not a lot of trade candidates out there. Go take a look at Cap Friendly's new filter feature (under Players > Free Agents, but you can select Active Players) and filter on RHD, 20+ minutes TOI, Age 22-25, and there just isn't a ton out there.
Stay the course, draft, develop. Lilly and Sandy are a couple of years out, maybe even next year in our bottom pairing for Lilly. Stralman would be a useful stop-gap UFA signing if we have the space, plus we still have Borgman/Rosen/Holl who need long looks.
The forward group needs to buy into the system; that's an ongoing struggle with offensive, talented kids. It takes a while for that to sink in, that they can't fly the zone and hope Gardiner can connect on a stretch pass every play. They need to be in a support position to help with the transition, and like Babs said, if you play a heavy game, cycle, and keep the puck in the other end of the rink, you don't have to play D, you don't have to get plastered on a relentless forecheck.