Arod's lawsuit will go nowhere and accomplish nothing. A federal judge will more than likely not even hear the case, but due to his celebrity he may get a courtesy "hearing".
The truth is that this is a collectively bargained process that was followed by the both MLB and the Players Union. Federal courts have never gotten involved with decisions made by arbitrators and won't want to start now.
His only hope would be to file a suit that his federal rights were violated, such as a claim of racial prejudice or something. The federal court will not touch this decision. Ever.
In reality, a 39 year old Arod in 2015 that has been out of competitive sports for a year may be forced to retire. He may not be able to make the team out of Spring Training next year.