Frankly I hope they do revoke the Church's tax free status, because then the Church would be free from the corrupt influence and pressure that the government exerts on it to remain silent on issues that affect not only our lives, but our souls. The Church would feel free again to speak its mind about evil, something that exists everywhere, even in the IRS.
There is no revoking involved. Churches have always been considered tax free, with or without any tax exempt status. This would be a new thing and something that would be at odds with the establishment clause and certainly the concept of Separation of Church and State. Being tax exempt has always been an assumed right of the church since the beginning.