Visa issuance the world over are designed to work exactly this way: to scale (foreign) labor up and down as needed. You may scale just the intake (if it is for permanent residency, like the much praised point-system used by Canada), you can also spin up or spin down the entire temporary visa labor force by changing the renewal and first issuance numbers.
I don't think any country invites and then carries out a massive purge of existing labor as it sees fit.
If it does, then it won't be appealing to the class of person you're seeking to attract.
Perhaps you could attempt to steel-man why point-based immigration allocate and de-allocate points for certain professions over time? Or why temporary visas exist in the first place.
> If it does, then it won't be appealing to the class of person you're seeking to attract.
Such is the nature, complexity and self-contradicting character of any large-scale public policy; and it's "classes" (plural) because immigration cuts across social strata, not just your software and service industry "rockstar" geeks.