I'm not sure where Arduino are coming from or heading too, except of course to get themselves into bed with most of the ARM based, industrial strength microcontroller producers. I'm wondering when they will officially announce jumping into bed with Microchip, ST and then NXP
From my perspective it appears Arduino are looking around at anyone making a good component, shield, controller etc and heading out and developing their own shields or adopting their own alternative products. Interestingly it seems to becoming more the case that the concept of open source is slipping away from the developers grasp. The form factor of the Arduino shield is based on the most obscure spacing, rendering the use of standard prototyping methods untidy e.g. breadboard, stripboard, matrix et-al.
Throw in the fact the confusion of shield voltages, many running at 5V while the processors are beginning more and more to heading to 3.3V. My understanding is that version 1.5 of the IDE is still not officially released, and the idea of getting involved with the DUE has no appeal, especially when the Teensy 3 is so stable and better integrated within the Arduino IDE.
There is a given 'maker' market, I feel that Arduino have the much larger world/volume in their sights, that of embedded microcontrollers, a market held securely by the main silicon producers. One core area they are missing out on if this is their intention and where PJRC have a considerable upside is integration of the microcontroller into a polished solution, you can solder a Teensy onto your main PCB, containing all your IO and with a robust (soldered) method to communicate the Teensy onto the board, of course utilising far less real estate, removing a lot of the power conditioning and delivering a professional looking solution within a commercial product.
With the decision to move to ARM processors there is one major, lacking issue within the Arduino IDE/bootloader/OS or whatever it gets named today and in the future, that being a multi-threaded environment, using ARM processors delivers a much wider range of hardware interrupts.
It would seem that 2014 could be an interesting year for Arduino, certainly with their current partnerships they are taking a lead from their ex-prime minister - getting into bed with anyone who will do so.
Indeed, while intended to be for the education market, the Raspberry Foundations Pi have shown the considerable hunger for us to head back to the 1980's era of personal computing, again, as a core small team they have achieved stunning results and know that they have a stable, robust solution to enter into their target market, as was referred to earlier, it's Google that have agreed to finance 50,000 Pi's into education. The difference between personal computing of the 80's and today is the availability of open standards, OS's, languages etc The only 'standard' OS in the 80's personal computers was CP/M but only if you were running Z80 CPUs then you needed to do a lot of work to move between different hardware, not least soft sectored and hard sectored 5.25" floppy drives and the controllers for both types.
Did the Raspberry foundation miss a trick with not making more IO available on the Pi? Personally I don't think it was an oversight, and if it was, there was a major conflict of adding IO to the Pi, namely the board is designed intentionally to be compact, easy to handle [by children] and with IO that meets educational needs and those of us whose eyesight isn't a sharp as it was in the 80's!
One last observation about Paul, it's spectacular what you (and your small team) have delivered in the line of Teensy products, especially when you look at the Teensy 3, you bucked the trend big time on Kickstarter, you delivered on time and a product that did what you said it would. Compared to the resource available to Arduino to develop their ARM based solution and the compatibility of libraries as you moved on from AVR, the rapid and seemingly positive way you worked with other parties to fix holes in libraries has to be said makes Arduino look rather silly for what they have delivered in a similar time since both PJRC and Arduino announced your ARM based products.
Time will tell. I'm not holding my breath though!