Originally Posted by 6strings
There are several issues to deal with.
1. Graphics cards. There are no real, working Thunderbolt-solutions for folks using those beefy, dual slot cards for 3D and heavy graphics work. Integrated graphics and smaller on-board solutions may be fine for audio and pro-sumer video, but is Apple really going to drop this segment of power users completely? I don't think so.
I wouldn't bet too much on that. Apple definitely want to keep "most of" the content creators happy (they'd have walked away from desktop systems long ago if that wasn't the case). But there's a real question over how far they'll go to keep the higher end of that market, and where the point comes when they decide they're ok with cutting them loose.
It's been said many times that they're a company with a 90/10 philosophy. They're ok with losing 10% of users if what they do satisfies the 90%. They're not hugely interested in servicing a small niche. That's not their focus. The Mac Pro line has become a small niche market to them. The main part of their company is also invested in bringing the PC form factor to an end. They're a consumer appliance company now (iMac + Macbook = appliances).
2. Power users. This is the BIG issue with video professionals (I mean the guys working in TV and film, not the weekend-warrior wedding photographer/videographer). I imagine a lot of GS members would find a decked out Mac Mini or iMac perfectly suitable for their work load, but there is a segment of power users out there working with video who require the power of dual Xeon processors; something you simply can't fit in a portable chassis (including the iMac) due to cooling requirements. Rendering and compressing video is VERY CPU-intensive.
3. Cooling. As many mini and iMac users have attested to, running these machines hard pushes them to their heat tolerances and winds the fans up pretty good. A tower machine like the Mac Pro has plenty of CPU and cooling "headroom" to do heavy lifting without breaking too much of a sweat.
Intel's main focus is on reducing power consumption more than anything else (Because their main competitor is no longer AMD - it's ARM). How viable such future solutions will be is still open to question.
What you're saying is true right now - This is probably part of the reason why it's going to take until into 2013. They're likely to be waiting on some sort of new product from Intel. I doubt very much it's just because they waited for the new generation of Haswell CPU's. Common sense dictates there's more reasons behind such a long delay. What those reasons are have some, particularly higher end users, worried.
4. Thunderbolt-only expansion = Spaghetti Desktop! A more minor issue, but I believe expecting professionals to hook up ALL their peripheral drives, devices, interfaces, PCI cards, etc. via Thunderbolt will mean a plethora of cables, power supplies and interconnecting cords cluttering up the desktop like you've never imagined! (never mind your multi-channel interface's audio cables) Hardly a "professional" solution, IMHO.
Apple love accessories. You're not thinking of the profit margins on those cables!
Remember that a future single optical Thunderbolt cable might serve as many things (monitor cable, CPU expansion, storage, and PCIE link etc.) But, yes, you might have to string things to each other more. Whatever they come up with, they've probably thought about that in some way.
These are issues Apple will have to consider when designing a new Mac Pro. Although many would love Thunderbolt to take over expansion duties, the reality is that there's more to a pro machine than the expansion slots, and even so, Thunderbolt adoption is going slow with definite no signs of picking up speed in the near-future.
There's always a delay between a new standard and the design and production of things which support it. Then there's the market lag until enough available machines allow device prices to start falling.
You're probably talking another 5 years before Thunderbolt really starts catching on. But I think we'll see much more stuff aimed at pro markets in 2013-2014. If Apple go in that direction then it will only serve to accelerate the process..