the BG variant can be 13mmx13mm or under - the T_3.1 is about 13mm?
Yes, I've had my eye on this 13mm size.
It's a very tight fit. It will not allow soldering header or sockets on the top side of the PCB, at least not with their plastic part flush to the PCB surface. But other than that caveat, and the incredible difficulty of PCB routing, it might fit. Maybe?
The smaller sizes are 0.65 mm ball pitch, which requires insanely expensive (at Teensy's modest volume) PCB processes, mainly via-in-pad, but also smaller than 5 mil traces and other high end specs.
Yes the new chip is awesome.
Yes, indeed it's awesome. The flash is also in 4 banks, which might really help applications wanting to write to flash.
The breadboard-inspired 0.1 in. pin pitch boards... I think are ready to be retired.
No, 0.1 inch pins are here to stay.
While there are a number of advanced users who need ever more pins, spi/i2c/uart/i2s/can busses, I suspect a lot of users are like me, and like the Teensy because it is easily used on a breadboard or perfboard.
Yes, the vast majority prefer breadboard compatibility with 0.1 inch pins.
If you look at the number one complaint about regular Arduino (well, ignoring the retail prices) it's the 0.16 inch spacing between headers!
Keeping that "Teensy" is the challenge, else we have yet another dev board like WaveShare.com sells.
Yes, it is a tremendous challenge. I'm considering a lot of different options....
Tough choices - I can maybe see why PJRC doing debug was the easier/better choice.
I do intend to do both. Currently debug is considered a higher priority. Believe me, that's not necessarily because it's easier.
When a ++ model happens, it'll almost certainly use one of the BGA packages. I'm not going to make a huge board like this with the giant TQPF chip.