The end of the the Ltd Co. agency driver?

robbo99.:
The crucial part of this legislation is that it only affects medium to large organisations, I can see lots of small agencies setting up to circumvent the rules, therefore continuing to use PSCs.

It isn’t the size of the agency that matters, it is the size of their client they send you to. From the second link in the OP:

Recruitment agencies
This measure affects approximately 20,000 agencies who provide workers to medium and large-sized organisations. They will need to operate payroll for any workers they supply who work through their own company and fall within the scope of the rules.