Noo! The mac pro is the only real desktop computer Apple makes. The slots and flexibility is what makes the computer. Thunderbolt is not widespread enough and is far more expensive than traditional ports offered in the Mac Pro.
Smaller isn't better imo (for desktops).
Whilst I do agree to some extent, the Mac Pro is really overkill now. Not in terms of performance, but its size. You could easily reduce its size (and weight!) without it having any baring on its existing flexibility. For most people the 'top' of the pro contains just the PSU and one superdrive. The superdrive is tiny now (as seen in the Mac Mini and MBP), yet the pro still ships with a bulky drive. The PSU is still a 'traditional' PSU, however again, these can be made MUCH smaller (again, the Mac Mini is a good example, but obviously the Mac Pro one would be slightly larger to allow for it's higher power needs)
Those two relatively minor parts alone could nock a good 15CM off the height.
Then there's the huge empty space for cooling behind the GPU's, the cooling on the Pro is excellent, but it's overkill. You could get away with a much smaller exhaust fan, taking a good 5CM off the height there, as well as about 8CM off the width.
The CPU fans could also be shrunk down a fair bit now. With the older models they were a necessity, but with the latest Xeon's you dont really need them that big.
This is all without even thinking about moving stuff around. You could even add more extensibility by adding an extra 4 HDD bays below the existing 4, or even adding 2 more where the unused optical drive space is.
Finally there's the case shell. It uses a rather thick aluminium...very thick actually. This seems to be solely for design aesthetics, as you'd still have perfectly good strength with a thinner alloy (such as those now in use on the MBP, iMac and Mini lines) which would make the case a fair bit lighter (and hopefully avoid razor-sharp cuts to the hands when you pick it up by the handles!!)