While I'm not against 3D printers, and do think they will make a very nice new "TOOL" in our arsenal of "TOYZZ", I myself see several things possibly being lost in the hobby.
Before CNC machining came along, Tool making, custom machining and pattern making were more of an "ART-FORM than a "Science, as it took skills not required in CNC work.
There was more pride in your work, as there were different levels of skills needed to qualify for a position, and be qualified to produce items from a blue print.
Now people just program a machine and walk away and the machine makes as many as you want.
I have already seen people making entire cars and kits on a 3D machine, and while this is great for all of us who want something that isn't mass-produced, and don't have the skills to scratch-build a non-existant model, I can see contest and rules changing quite a bit when everything that is really good was created by a machine, and all that's left to judge is finish, paint, detail and assembly. Maybe there'll be a separate class.
For me what would be lost as a scratch-builder is the pride of using the disciplines I have acquired over the years to create a part, or create a body by hand and the sense of accomplishment I get from a hand crafted part or entire finished model
Eventually I will probably buy one, but limit the usage to "Novelty", as staying a craftsman and using my skills that took years to develope, allows me to keep enjoying the hobby for the reasons I was first attracted to it.
Old School and New School meet somewhere in the middle .