Despite Wayland's slow pace, it's still vastly ahead of Mir at this point. I acknowledge this, and I will even say this presents some interesting challenges to those developing Mir. It's also important to note that the upcoming release(s) of Wayland will likely bring forth the missing functionality, such as minimizing and maximizing windows. And if this happens before Mir is released, this will put Wayland much farther ahead of Mir.
What's my response to this possibility? Awesome! Because this would give us two great display server options to choose from as time passes along.
Remember what I said previously, this isn't a zero-sum game. Competition between the two projects only serves to benefit Linux users collectively. So if Wayland comes out the winner for the desktop, with Mir being useful only to Ubuntu, I'm completely fine with that. What I find so perplexing, is all of the complaining about something that isn't a threat to Wayland within the Linux community. It makes little sense to me and offers no value to anyone.
In my effort to better understand the paranoia about Canonical "seizing control" over the hearts and minds of Linux users, I've come to the following realization: The Linux community includes people full of passion and opinions. This is especially true when it comes to developers. Speaking as a non-developer, I have the advantage of looking at this with indifferent eyes.
Another individual brought up a fantastic point that I wanted to share. They mentioned that despite the code being open source, Canonical might force video card vendors to stick with Mir standards only. After all, their rationale is that video card vendors aren't too likely to support X, Wayland and Mir. Now this was a solid question worth exploring. My view on this is as follows: whichever project wins in the long term will be in a position to work with those building video cards. If this happens to be Mir, other distributions will be free to follow along or not.
As I bring this to a close, I want to acknowledge that there are a lot of heated debates and some strong opinions floating about Mir vs. Wayland. I maintain my position that either the best option or perhaps both options, will come out ahead in the long term. My view is that Wayland has had years to get a working product (and, no, it's not there yet in my opinion).
Currently, Mir is very much still in the concept stages; however, I've seen Canonical on a development warpath before. And no matter what you may think of them, they do development quickly. Based on a wide variety of factors, I think we'll see Wayland win early on with their display server offering, while the Mir team catches up later.