If you were a designer working for Apple, how would you redesign the Mac Pro?
AND make it a viable commercial product?
it doesn't need much of major re-design (besides making it more easily rackable. Reining-in or making optional the handle height and dumping at least one of the ODD bays should be enough. ).
There are a couple of things that Apple could do relatively easy that would make it more viable.
1. as noted above perhaps replace two ODD drive bays with one external lockable 2.5" sled drive (refactored XServe sled). The objective is to increase sales a bit by making Mac Pro a decent 4U rackable box.
(sure there are folks who need thinner models since designed datacenters around 1U boxes but there are lots of situations that only require 2 or 3 boxes and 12 U is available. )
They need a config that is just Mac OS X Server with a easy replace 2.5 drive.
2. Let the Mac Pro prices drop down close the $2,000 barrier. The iMac gets to roam freely in the $1000-2000 range but if it wants to poke its head into the $2000 price zone then the gloves are off. The two Mac compete head to head.
[ over time the iMac has creep higher and higher into the price zones that the tower (Mac Pro) operated in. I'm not saying Apple has to reverse its "no compete and cannibalize zones... just don't push the Mac Pro increasingly higher. Pushing higher kills sales. ]
2. Put embedded graphics option ( pull a common iMac graphics board that is OpenCL capable to share component costs and keep R&D low). A sub $2,400 model would come with no video card, minimal HDD , and minimal (4GB) RAM. The folks who just want a "box with slots" could buy a $2,099 or $2,199 box. Those who want to fill it up with 3rd party disks, memory , and grahics cards can.
This also makes adding TB standard much easier also.
[ At some point Intel is likely going to put a integrated GPU even into the Xeon E5's. Once the transistor budget gets high enough that have room for it. Once Intel's integrated GPU can do GPGPU it is also like putting an "extra" FPU into the chip so even servers can leverage it if need be. It also simplies server lightweight need for graphics if just absorbed into core major chips also. ]
3. Better OS software to more efficiently manage the Mac Pro's hardware. That means threading/NUMA/etc aware optimizations sooner rather than later. [ it is not like the other macs aren't going to pick up the issues later when they get more cores and the arch features in the Xeon. ]
Similarly, there should be no need for a card to enable a RAID set-up using the for internal drive sleds. (i.e., they should render the Apple RAID card obsolete).
4. A better GPGPU platform. [ Apple needs to grow the market of folks who will buy these. At this point workstations are for people who need personal supercomputers (or what was a supercomputer 5-10 years ago. ) ]
There are some folks using Mac Pro for this but Apple doesn't have support for this.
It isn't just PCI-e cards that are important to sustain the Mac Pro. It is high I/O + very low latency PCI-e that will fit the market or not. The pedestrian PCI-e cards are going sucked up by Thunderbolt.
5. Better, 21st century software that isn't hobbled by artificial single threaded roadblocks. Right now the Mac Pro suffers from a large glut of legacy software that can't fully leverage the capabilities present. That makes is hard to get maximum value for money spent. FCPX is a step in removing that glut but there is lots of other pieces to the puzzle.
[ Apple invests in new Flash memory and LCD display facitilites. This is similar. They could put some bounties out there for folks to remove the cruft some software and perhaps recoup with a higher MacApp store taxes on that software. ]
In the very long term the Mac Pro does have a problem of how to put more value into the box since it is constrained to the over $2,000 price range. Over time it may die off because enough user problems all fall out of the $2,000+ worth of hardware needed zone.