That is a great fall-back strategy if Mir ultimately fails. Ubuntu , and most of the Linuxses , all have these fallback features. I am to understand that mir will talk to x and wayland etc.. so perhaps they will all get along. Not only do we have choice of Ubuntu flavours but choice of display servers.
For now I have X which meets all services and then some .. so there are no complaints from me. If compiz and ccsm fail in Raring then I have no problem locking Lucid Lynx and running a customized version of Ubuntu on my big machines. In front of me, leaning on one of my KVM units I have the 4th Edition of Running Linux 2002. Matt Welsh .. etc.. and it is rather outdated. I like moving on to new things. I gave wayland a good try and then it just stopped progressing. Maybe it's just me. Anyways .. one of my jobs in my early career (before floppies and hdds) was to disassemble mechanical relay modules, troubleshoot them , test them , repair them and reassemble them. They were just basically small units of a total larger unit. When Microprocessors first came out I troubleshooted VAGs for cold solder joints. Part of my expertise way back then was to find microfractures in seemingly good solder joints that were acting as circuit breaks. Even as the PC revolution took off I still repaired MoBo and inspected them for cold solder joints. I still do this to this day!!
I like doing the same thing with blocks of code. The 'mir' executable in /usr/bin/ is a small block of code that makes calls on many other objects and components. I like to disassemble all these things. Why ? It's just what I do. I think to myself that perhaps I might ask a question or contribute somthing to make mir better or move along .. or maybe somebody will come up with even a better alternative.
I think I stated before in another forum that my eyesight is becoming diminished with age. The Unity desktop in current Ubuntu gives my eyes a soothing effect unlike other desktops. I am not sure I want to spend too much time trying other desktops (as I have experimented with quite a few already). So that brings me here, hoping that 'mir' will succeed and hence also Unity. The wayland team is big enough. No? So why should I spend time disassembling wayland when I can disassemble mir?
However .. you bring some good points to the table to be considered definitely.