I've actually been toying with an idea like this, but it would take more than a middling prospect I think. Ehlers is a skilled player signed to a reasonable $6M deal for 6 years, and that's valuable.
I was thinking #29 plus Sprong and Lundestrom. They get a good prospect and a body with some scoring ability to fill the hole Ehlers leaves. This is a draft day deal, because it's easier to do if it looks like there may be a center still available at #9 to replace Lundy. It's why I argued about trading a pick to get Stralman so we can talk to him and maybe get a deal done by then. If he's locked up, we don't have to worry about possibly needing #29 for a defenseman.