A large number of freelancers & agencies have built a stable clients on Upwork from years together. It will be a little revenue shock for them. Or eventually clients will pay more to cover the costs.
Let's assume you are a freelancer with a client relationship of 40k
* 20% fee for the first $500 earned from a client - $100
* 10% fee between $500 and $10,000 earned - $ 950
* 5% fee after the first $10,000 earned - $ 1500
New model - 40k
Am I missing anything here?
* 10% fee of any amount - $ 4000