If you can get a first and a top prospect, I think you must consider it, but a lot depends on who that prospect is. Personally, I would need to see a forward with high end skill. The first-round pick would obviously be in the last 3rd of the first round but that is nothing to scoff at. Yes, it will hurt to lose Hagel, but this team will not really be able to take advantage of his deal and his value might never be higher, and his play style makes him prone to injury.
Example: If the Rangers offer a first-round pick and Vitaly Kravtsov, you 100% have to consider it.
To be clear, you don't trade him just to trade him.