Does this mean Stripe will phase out the ability for Canadians to accept USD and deposit funds directly to Canadian banks offering "US fund" accounts (that are not technically US bank accounts)?
Currently, a Canadian business can accept $USD with Stripe and have it deposited directly into a Canadian US fund account without conversion to CAD.
Stripes competitors can't do this - and have traditionally told Canadian businesses that they would have to incorporate in the US, setup a USD bank account at a US institution, in order to accept USD without conversion back to CAD.
That process is what Stripe Atlas simplifies.
PayPal allows Canadians to accept USD by holding the funds in a USD PayPal account. However, getting the funds to a Canadian bank account always involves converting to CAD.