Why would they partner with Wasabi if they were planning to run their own coordinator? The Trezor team are more than capable of building their own coinjoin implementation and integrating it with Trezor Suite without Wasabi's help. The only reason I can see for the partnership is to give Trezor users direct access to Wasabi's liquidity, but that comes with all the downsides of using Wasabi's coordinator.

Better hope Trezor don't start "pre-screening" all your addresses for coinjoining by sending them to Wasabi's blockchain analysis partners for vetting. But of course, we would have no way of knowing one way or the other.