It seems pretty clear that it is highly unlikely unless something changes quickly Trent Richardson isn’t going to make the Raiders roster.
If he can’t make the Raiders roster, I doubt we will see him ever again in the NFL.
According to PFT, the Raiders put him on the NFI list, meaning he isn’t hurt, but something happened (conditioning maybe?) where he will be held out of practice until whatever the issue is has resolved itself.
There was a report on the first day of camp things weren’t going well for Richardson, I would say this confirms that report was true.