I've been following the MKR series for a bit. 32bit ARM Cortex-M0+ @ 48Mhz core , memory capacity of the Mega,
Although not a fan of all of the varieties (lora, sigfox,), the original MKR Zero including a microSD was good, the MKR1000 had Wifi for allot less than the YUN. Really liking the MKR 1400GSM & MKR 1500 NB (need to learn more about connecting with this) and the MKR 1010 WIFI (a reboot of the MKR1000). Having the built-in Li-Po charging/swithching circuits is really good.
Anyway, this MKR format seems the way to go..... much better than the old beardboard unfriendly UNO/MEGA R3 layouts that every single Arduino board before used. This MKR format is the future for Arduino.
In the future, we may see a better equipped/supported successor to DUO/MEGA that might use a Cortex-M33 or Cortex-M7 core in a stretched MKR format to give us access to many more pins, multiple channels of UART, SPI, I2C, I2S, MIPI DSI & Touch interfaces, microSD, and a BLE, Wifi, LTE NB comm interface. That would be cool stuff to see in an elongated MKR format.