This is a change to the law. Previously, pilots would either need to fall into the special category created for Australian pilots only or would need to show beyond exceptional skill (think test pilot or something like that) where no American could do the job. Now, any pilot with the requisite experience and pay grade in their country can apply for and receive a green card without having a job first, which is a huge change.
And no, Atlas are not the only ones who will benefit from this. The regionals have been getting crushed by flow to the mainline legacies and LCCs and that will only continue. The mainline carriers are also going to feel this, as the training pipeline just can't keep up with the retirements and expansion.
The big losers on this are going to be the ME3 and Cathay, especially if they keep on abjectly abusing pilots. There is also a thought that there will be an influx of Indian pilots to the US.
This is mainly for Atlas Air
Regional airlines (the less desirable to work at ones, at least) have been brining in foreign nationals for a few years.
Not just the less desirable regionals. They pretty much all are. There are quite a few Australians working for SkyWest.
That is under a specific visa category reserved for Australians.