You have good points but there is no way that the costs wouldn't blow the ceilings off if those measures are taken as is.

I do agree that the immigration system is broken. But I do not agree that immigrants are the problem. Simply retroactively applying rules to the folks who are literally accepting to be exploited is not only unfair as immoral, unless you do not consider them people.

I would need to check the gov docs again for the maths, but if this triggers high skilled workers to leave (and only them, not even counting other side effects) it would cause a 2B-4B blast in the economics.

And this do not even consider possible causes of returning the money from pension partially or fully.