Sadly I feel to have to refute you somewhat:

Will it never happen in the US ? Quite probably.

Europe ? China for that matter ?

If the terrorist sucess rate remains at it’s comfortably absymal low, very unlikely.

But I fear that should the terrorist get one maybe two good licks in, a dirty bomb maybe or VX in a stadium, I fear that even the pretense of deporting them elsewhere - and remember that one of explanations given for trains full of jews heading east was deportation - will be gone from the mouths of these demagogues. And even more deeply I fear my feeling that they will find a willing audience then.
And not even the US is totally free of this danger, ask the indians. But far less probable for that to happen in the US.