It doesn't anything there about opting out, it seems everyone will have to be on the new system eventually.
Says this in the article.
You don't need to do anything until you get an invite, which will come by notification on the eBay app or by email. eBay says you just need to follow the instructions to add a bank account, which should take a few minutes. Once you change, you won't be able to get paid by PayPal.
If you don't do anything and continue to use the existing service rather than switch over, eBay warns that it has the right to restrict your ability to make new sales listings and to change or end existing listings.
Although reading it a bit more, don't know if this prevents higher fees.