Maybe it's time to share (or "leak") a few Teensy++ 3.x details, even though the product is still pretty much in the planning phase.
Here are 5 things that are absolutely certain about Teensy++ 3.x:
- ARM Cortex-M4F (Floating Point Unit)
- Under $30
- More I/O pins
- More serial & SPI ports
- More memory
I'm leaning towards a 48 pin form factor, with an extra 3.3V & GND pair. I'm still debating whether AREF should be brought to the outside breadboard-friendly edges. Likewise, I'm considering whether the to bring out some analog-only pins (like A10 & A11 on Teensy 3.1), which offer perhaps lower noise and differential analog signal input, but they can't be used for digital. Total number of digital pin on the outside edge could range from 35 to 40 or even 42, depending on whether some pins are extra power and analog only stuff.
I'll very likely put a Micro SD card socket on the end of the board. The "large" applications where you use such a powerful microcontroller often need storage, so that seems like a good use of the extra space (from making the board longer). But perhaps that extra room could be more useful as lots of through-hole pads for extra digital signals? In theory, you could always add an adaptor for storage, but my gut feeling is in practice many applications use storage media.
Also, while I'm spilling rumors, PJRC is working on a lower cost Teensy 3.x based on an ARM Cortex-M0+ chip. It will feature similar I/O and peripherals as Teensy 3.1 (except the bottom pins), with less memory and a slower processor, but a retail price in the $12 to $14 range.
We don't have any hard deadlines for these new products. I can tell you I'm very committed to working on the software support side, which often comes at the expense of working on making new hardware, so it's quite possible both of these may slip for quite some time.