That's why I was wondering. Since the Blackmagic eGPU is a separate GPU, perhaps 3 monitors concurrently will work. It's so new, I haven't actually been able to find anyone who has tried it yet.

Of course if it is a software limit, there's no sense in trying to wait for it to change. Apple will do what they please when they want to do it. It will be best for you and you WILL like it.