As the Blazers noted in their press release announcing the trade, the 2020 second-round pick they sent to Orlando is heavily protected, specifically "from picks 31 through 55."
In practical terms, this level of protection means Orlando will only receive that pick if Portland finishes with one of the league's five best records that year.
Trading a former first-round pick for a future second-rounder isn't great asset management; that Orlando essentially punted Harkless, after investing three seasons in his development, looks at first blush surprising.
But when one considers that Harkless' playing time dropped in each of his three Magic seasons, and that Orlando added Mario Hezonja to a wing rotation which also includes Victor Oladipo, Evan Fournier, and Aaron Gordon, the trade makes a bit more sense. The Magic have some young talent on the wings but only so many minutes per game to devote to their growth.
And yet it's easy to understand fans' frustration with the end of Harkless' tenure, one which started with so much promise. Harkless always came across as hard-working and humble, and his bursts of brilliant, athletic plays--such as this series of rejections on Carmelo Anthony--got fans excited and hinted at his potential.
Ultimately Portland and Harkless himself are the only real winners in this deal. The Blazers, squarely in rebuilding mode following the free-agent departure of LaMarcus Aldridge, get a free look at a young wing with plenty of raw talent ready to be harnessed. And Harkless moves to a team more ready, willing, and able to develop him.