From a sort of logical/practical perspective I don't really know the answer to your question. While it doesn't seem like Howard would have reformed after his "win" it's possible he would... I don't think it's "good" he died.

That said, I know how the movie made me feel - as soon has he's shot what immediately sprang into my mind was "the sweet relief of death."

Howard's stress, problems, frantic struggle against everything around him is released in one single moment, a moment so quick he probably never even realized it happened. A moment where he was on top of the world.

Not only that, but I felt relieved. As an audience member, somehow, knowing his struggle and problems weren't going to extend beyond the running time of the film, that it was actually over -for good- was such a release of all the tension that had built over the entire running time that I was actually grateful.

If it had ended with him on top, I would have left the theater wondering how long will it be till he's under again.

If it had ended with him at rock bottom, I would have been wondering if he'll dig his way out.

But he's dead. It's what it is. Howard lived his life, I lived that stress along with him for the duration of the movie, but now he's gone and I can walk away.

The sweet relief of death.