You can't bank on a goalie prospect. Ever. Goalies are generall too flaky.
Which is also why I would not trade Howard for anyone at this point. He shows signs of brilliance, can carry the team, and is a workhorse. Not too many of those in the league, and in today's NHL that's all you need. What good is an elite defenseman if your goalie sucks? Howard has at least shown he can bail out the team when they lapse into bad defense. Ergo, he is more valuable.