I haven’t tested it but here’s how I see things according to what I’ve read. In the case of the 301, it will give the ability to control the sound computer in many different ways.
Here’s how I’m planning to use it:
I’ll use Norns as a hub, Norns (or a simple Raspberry Pi running Norns) will be connected to Crow via USB and Crow will be connected to the 301 via I2C.
One can connect anything to Norns, Midi keyboard, Linnstrument, Monome grid, midi faders, 16n faderbank or even Bluetooth devices like Roli blocks (Norns code needs to be modified a little bit for Midi over Bluetooth but that’s another topic), OSC devices and apps.
You can write a complex sequencer (Norns lua script) controlling the 301 for example, and on top of that, Norns can convert some external MIDI to Teletype protocol and transmit all that via I2C (I hope the connection is super strong) I imagine that most of the existing Norns sequencers will be updated for using Crow as a possible output. Anything Norns receives may be converted and sent to the 301 using a custom script, and LUA scripts are quite easy to write. So Crow is a communication tool. Grid + Norns scripts + midi controlling the 301, that’s my plan, I do hope it’ll work and be super reliable as I imagine it 
Crow can also be used in standalone mode, without Norns, it can host some LUA scripts, you can even do some live coding and control Crow with a terminal (? Haven’t seen this yet , Its similar to Maiden but it’s called Druid) + The 2hp module has 2 inputs and four outputs for talking to the regular modules without I2C or to the 301 through it’s hardware cv inputs and I believe the amount of outputs can even be expanded with some Txo modules but a script needs to be created for that too, it should be easy according to the creators of Crow.
There are also some M4L devices and Max objects created for it. I believe it supports Ableton Link as well. This opens up even more possibilities…
I m sure we’ll see many demos and use cases in a week or two.
If you don’t own a Norns there are now 3 different diy Norns projects available including an official one which allows you to include this powerful device in your setup for about 100€. Again, Norns is totally optional with Crow, using Crow with Max for example might be really fun and super powerful as well !