The Mac Pro, Apple's only computer with expansion slots and bays, is on its last legs.

Apple last updated its venerable tower PC in July 2010 (adding 12 cores and SSDs) more than 2.5 years ago, 932 days to be exact. While the Mac Pro received a minor CPU speed bump in June 2012, it didn't receive critical upgrades to technologies like Thunderbolt and USB 3.0 that pros need.

While there have been some hints of a new Mac Pro (1, 2, 3 ) there has been no official word from Cupertino short of a vaguely worded email from Tim Cook last summer, saying that "we’re working on something really great for later next year." If Apple does upgrade the Mac Pro, it might even make it in the United States.

My question is: who needs a Mac Pro anyway?

I understand that video professionals and major pixel pushers need as much horsepower as possible. This often includes copious amounts of RAM (the current Mac Pro can support up to 64GB of RAM), four drive bays, a discrete GPU, and of course, slots.

The iMac maxes out at 32GB of RAM, has an anemic GPU, no bays and no expansion slots. However, as my colleague David Morgenstern points out, an iMac can be expanded with " JBOP " (Just a Bunch of Peripherals). It can support PCIe expansion cards via a breakout box connected to its Thunderbolt port. While not as elegant as a spacious tower, it can be done.

So, while use cases exist for high-power Macs loaded to the gills with drives and cards, what percentage of Mac users actually buy them? I suspect that most professional Mac users that got tired of waiting for a new Mac Pro upgraded to either a retina MacBook Pro, an iMac JBOP, and/or a Mac mini connected to a massive storage array like the new Drobo 5D.

You: Apple CEO

Put yourself in Tim Cook's shoes. Would you invest the R&D time necessary to create a new Mac Pro? Or would you put those resources on more profitable product lines?

Apple could probably squeeze another year of life out the current Mac Pro ("cheese grater") form factor and simply release an invisible upgrade with support for the latest Intel chips, Thunderbolt and USB 3.0, but that's not really Apple's style. Apple likes to go big with hardware re-designs and the Mac Pro is overdue.

Enough people have complained about the lack of a new Mac Pro that Apple will probably have to act. If Apple releases a new Mac Pro I would vote for a new enclosure that works as a tower but could also be rack mounted. This would get pro users back into the fold and potentially delight enterprise users as well.

While we anxiously await Apple's decision, here are some Mac Pro concepts from Scott Richardson to drool over:

Further reading: