I don't know the future, but it is important to remember that the list of countries came from a failed nation list made by congress and the Obama administration (they also included Iran) [1]. Trump did not just pull it out of the air.

Green cards are also permanent residences so legally that is much harder to stop than not extending or granting new visas.

With that said, I'm against it and think it is bad policy on many fronts.

[1] http://www.cnn.com/2017/01/29/politics/how-the-trump-adminis...