20-Year Prospect
You should have no worries that criminal justice jobs will disappear.
We've tried outlawing crime. It just didn't work.
As long as people are people, some of them will be criminals. The positive side of that is job security for wannabe CIAs. Technology will change certain aspects of the field in the next twenty years, but it's doubtful we're talking about robot guards or implanted tracking devices.
Okay, maybe there will be robot guards and implanted tracking devices. But they won't be able to replace humans, just aid them (hopefully). If you're willing to put in the time, you should be good to go. Every organization needs a boss.
However, as with basically every other field and industry out there, standards will probably rise. In twenty years, you might be required to have that criminal justice degree earlier in your career. Or maybe you'll need paper proof that you've taken business courses, because the prison is sick of crime-savvy but business-stupid CIAs.
The general trend in the USA right now is, "The more qualifications, the better." Get that bachelor's. Heck, get that master's. And above all else, get that experience. No degree will ever be able to take its place.