I'm sure their costs and efficiency will improve. As usual. ;)
They advertise Arduino compatibility, so I'm assuming that means compatibility with the AVR instruction set, but I could be wrong about that.
But that's just Arduino, i.e. high level compatibility. You have a setup() and a loop() and the same way to do I/O, but not the same underlying instruction set.
The chips on these guys are regular ARM cortex uCs.
They might be just barely fast enough to do real-time emulation of the AVR INSNs though ;)
Other major competitors are NXP/Freescale, ST, TI, and Infineon.
Chip design and manufacture, however, I can easily believe converge toward a monopoly, mostly because research efforts compound like crazy.