"Next year I am going to Japan."
Yeah, it can be either. へ Is still used even for a proper destination sometimes. I think it makes sense for the future tense because while you might intend to go to Japan, you might still change your mind.
It took it fine, for me. It's just one of those sentences where they want you to use Hiragana for 私 for no reason, despite it being implied. As far as I can see, anyway...