I'm from the Coco community so I'll try to make a case.
Many peripherals were developed over the last few years, notably:
- the miniMPI, which allows 2 cartridges to be inserted at the same time
- the cocoSDC, which replaces a drive controller with a SD card reader
- various VGA video adapters
- joystick and keyboard adapters
- hi-res mouse adapter
- a cartridge with an integrated 8-bit audio chip is being developed; games on cart will have better music and sounds
- a better 512kb memory expansion board which generates much less heat
- replacing the Motorola 6809 with a Hitachi 6309, which allows additional opcodes, and paves the way for more efficient programs
- drivewire, which allows you to connect your Coco to your PC through a serial-to-USB cable, for file access and lots of other functionalities
- the hardware community is very active and is actually gaining momentum
On the software side, lots of projects as well:
- homebrew games such as Popstar*Pilot, which looks gorgeous
- Fahrfall, first physical cartridge game to be made in the 21th century!
- NitrOS9, an OS9 distribution with lots of recent improvements, manages up to 2mb RAM, runs multiple programs simultaneously
- text editors, file managers, etc., for OS9
- Donkey Kong Remastered, which takes the actual arcade code and ports it to the Coco3 while adding new levels
- music trackers using the 6-bit DAC
- my own homebrew game project (Kaboomerang Kim), which is still under development but looks promising
- many projects and programming challenges in the community
- most projects target the vanilla Coco2 or Coco3 (128kb or 512kb) which means any physical machine or emulator will run them
Events
- The annual CocoFest in Chicago, after a few "calmer" years, is getting more popular
- Tandy Assembly event in October 2017
- Coco/Dragon events in Europe
- etc.
Tools
- The LWASM suite makes it easy to compile 6809 and 6309 code
- Lots of documentation online, including modern reference materials in PDF
- A cocoSDC distribution which contains pretty much everything ever released for the Coco
- Three emulators actively maintained: VCC, MAME/MESS and Xroar
People
- many Coco enthusiasts, dubbed "coco-nuts", are very active online
- 2 series of podcasts covering lots of subjects and letting people participate live
- some of the iconic/legendary developers drop by from time to time
ps: A video showing recent developments in my game project Kaboomerang Kim: