That package for Kane is possible, but it's probably not reasonable to expect that kind of return for Kane. Teams don't usually trade their top prospects for rentals, it happens but it's not at all common. Kane also has the attitude issues that players like Hossa (Esposito was the top prospect in that deal) and Iginla (talking about the rumored Boston package with Khokhlachev) didn't have as rentals. I don't think it's reasonable to expect that kind of package for him, and I certainly don't agree that Hagelin has negative value.
The Maroon trade is also pretty bad, I'm not trading a good prospect and a 2nd for a complementary player who's a rental. I'd sooner just try and trade Hagelin for someone like Colin Wilson from Colorado.