There are tax implications along with other problems with outsourcing your own job. There is no direct supervision to make sure that employment laws are followed when someone is acting as your proxy for example. You are responsible for your work product, and if that person for example leaks sensitive company info, the US worker is liable.
Outsourcing one’s work to attempt to earn profits through overseas workers has already been a “big thing in the workforce” for people. It’s nothing new. In fact, it’s so big that people who don’t outsource their own work still get accused of doing such because so many people are. I think it will die off, however. Companies are trying to put protective measures in place to make sure people don’t that. Aside from that, it will become less attractive as the outsourcers find that they often have to go behind the “Chinese worker” and spend a lot of time on the projects anyway. It’ll become unattractive quickly after a few such cases.
This doesn't seem like it will catch on, mostly because employers will not allow it. They hired a specific person to do their job, so why would they pay that person to have someone else do the job? In certain jobs, especially for freelance or contract workers, this might be possible, but for actual employees, I don't think this is a reasonable possibility.
Outsourcing your own job sounds cool; however, it will not likely become the next big workforce trend. The American IT worker that outsourced his job to a Chinese worker was eventually discovered by his employer. Most companies maintain adequate controls to ensure that events like this one cannot happen. Unfortunately, many companies continue to outsource American jobs to third world nations against the wishes of the American employees losing their jobs.