The skit is worth watching (imo, in light of this debate), for those that can stomach it.
This is the spectrum as I see it:
1. Not wearing blackface - acceptable
2. Wearing blackface as a way of demonstrating how horrible is it is - not acceptable
3. Wearing blackface as a way of demonstrating how horrible is it is but also for shock comedy - not acceptable
4. Wearing blackface to 'respect your favourite black ______' - not acceptable
5. Wearing blackface for shits and giggles - not acceptable
6. Wearing blackface with the explicit intent to mock/marginalize black people - not acceptable
They did #3. Her character is meant to be terrible and ignorant and the explicit theme of the sketch is 'wtf you can't do that' but that can't be a vehicle for therefore doing whatever you want. It shouldn't be a vehicle for entertainment. Since she owned and denounced it, I personally wouldn't promote the idea that she should be 'cancelled' or change my consumption of her content (I think Mr Show might be the only thing I've seen her in?). I think this particular example is something someone should be able to come back from. But I also don't fault anyone for choosing to fire her for this.
Also, her comment about sticking her neck out was fucking stupid. She's obviously upset, having expected that apologies, remorse and time would be enough, but saying shit like that won't do her any favours.