Re: "This measure is expected to impact 170,000 individuals" . . .
. . . who will be off to the EU within the next year,
A little bit uninformed comment. A lot of them are already in the EU. There's a huge number of contractors working in Germany, the Netherlands, France, Belgium and so on with a contract registered in the UK.
making a stonking big experience hole in what the government has available
The hole will probably be in the employer expectation who are using the scheme to dodge labour rights, but they'll probably work around the issue by moving the contracts to Ireland.
If they are intelligent enough to fend for themselves, they will not blink at the prospect of expatriation ...
Trouble is that even those intelligent enough to fend for themselves don't have a lot of choices. The nomber of contracting jobs is rising all over Europe because the schemes brought in by British capitalism worked very well to erode labour rights.