They can be very expensive. Idk how people will coinjoin with unavoidable high fees in the future
Discussion
The WabiSabi coinjoin protocol allows you to send your payments directly within a coinjoin so extra costs are minimized to only a couple of extra outputs.
That's why you'll coinjoin directly into a lightning channel in the future.
Onchain won't be used for regular payments, rather to enter and leave second layer solutions, but coinjoin is still mega useful in this case.