[Jay.]

Nothing mentioned by the BBC Trust has indicated that the BBC Three brand would disappear, so I'm not sure why people think BBC Four would be an unsustainable numeric in the 'family of channels' on offer (especially as it started when BBC CHOICE was still broadcasting).

Having 'one', 'TWO', 'Three (online)' and 'FOUR' is no more illogical than ITV removing the numeral from their premier channel and yet retaining 2, 3 & 4. It's not gonna make sense unless the BBC act fast.