There's nothing in the article that says CSX can't or won't hire another contractor in the future.
One of the benefits of hiring a contractor is greater flexibility. If I don't like your work, I drop you and I get someone else. This is not possible with the labor protectionism that unions advocate for. That appears to be what is happening with CSX. I recommend that you read beyond the article headline.
Your (union) jobs in jeopardy mosty due to the incompetence and aloofness of UP executive and departmental leadership, but the unions also played a role by demanding too much in terms of pay and benefits in return for too little added value for the company in relation to labor costs.