That they're flirting with a Cortex-M0 pathway probably suggests they don't want to keep developing another generation of 8-bit platforms after the Dx series. If they bring the same features to another CPU core, I guess that's fine.
That being said: AVR Ex series still has features that the PIC32 CM cannot do. I wouldn't say that the AVR is dead yet. But Microchip is beginning to hedge their bets. So we should keep an eye on future developments.
And 1.8V operation across the board still solidifies the AVR as the low power king (or at least, tied with the PIC series). Even if it's now sharing its 5V crown with another chip. I guess 5V always made more sense for the bigger and (slightly) less efficient 32-bitters.
The "PIC32" name was originally used for MIPS CPUs but more recently ARM ones and PIC32A is an extended dsPIC (16 bit).
There is also now PIC64 which is currently a couple of different RISC-V implementations, one based on quad core SiFive U54 from 2018 (same as PolarFire SoC FPGAS), and higher performance (and rad-tolerant in some versions) octa-core SiFive X280 with vector processing. Microchip have I think also indicated there will be future Arm-based 64 bit PICs.
The documentation on PIC or AVR assembly is extremely short, less than 200 pages. But the chips other peripherals (MVIO, 50mA push/pull current at upto 5V, OpAmps, differential ADCs, Event systems, and more) is where these chips get a resounding advantage.
Except now PIC32 CM has those very nice peripherals (comparable to AVR DD at least). It's very curious to me how it all works out: if Microchip will continue porting their nice hardware to ARM, or if they'll continue to develop new stuff for the 8bit market.
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Because the peripherals are hardware, I don't think it's really too valuable looking at the assembly language or other comp-sci details. The 8-bit assembly languages, be it PIC or AVR (or 8051) are all sufficient. Enough CPU to do things and glue the peripherals together.