Or, it's good for the marketplace in that there will be more choice for consumers and lower prices all around, with a lower cost of entry to those who wish to produce. The industry will also have a larger, cheaper talent pool to select from, lowering their costs. Markets will open up for custom parts that didn't exist before. LOTS of money will change hands, stimulating the economy. Lawyers will benefit because this surely will be a hotly litigated subject for the next few decades.
Those who already work in the industry probably won't be supplanted by this anyway. Designing for a run of 10,000 is a different skillset than designing your own Iron Man Mark 1 action figure and hoping it doesn't crash your MakerBot.