While the price trend on TCGPlayer was trending downwards back in 2016, it was doing the opposite on Magic Card Market in Europe, and still is. It's also popping up in more Commander decks than ever. This is due to the massive supply available because of how many Battle for Zendikar packs have been opened. As a mythic rare that is definitely playable, now is probably the time to make sure to have a copy or two of this card stashed away.
The Outcast was once a $15 card when the Worldwake printing was the only one available. While it may not reach that level again, it's not out of the realm of possibility that Dragonmaster Outcast becomes a $10 card again some day.