Seattle will let Willson test the free agent waters when his rookie contract expires.
Sure a blocking tight end is coveted, but this new guy from Stanford is almost Gronk size and his college coach, Urban Meyer, basically described Vanette as a receiving tight end that didn't have the bench press punch to block at the point of attack (Rewind the NFL Network draft DVR and listen to his comments). After having to prepare for Gronk in the Super Bowl, I think there is more to this than just a blocking tight end. I think they want a huge red zone target.
Don't get me wrong about Willson either. He is a solid player and a much better blocker than the pundits here at .net give him credit for. I have seen him make more than a few crunching blocks. Willson has great in line speed for a tight end. My only knock against him is that his catch radius doesn't match his length. He doesn't drop balls, but I don't recall any circus catches either. Russell's accuracy minimizes the issue. Regardless, Willson will find more money elsewhere than what Seattle can afford to pay. Seattle has to keep a certain percentage of their players under rookie contract. It isn't like the staff wants him to leave. They just have to make hard monetary choices.