BBC3 is/was an test bed for experimental new comedy and drama, and yes - whilst there always has been a commissioning process which has served the corporation well, I doubt that half of the successful comedies and dramas we have seen on BBC3 would have ever made it to air had the channel not existed.
It isn't a BBC Policy to launch shows on one channel and then progress them to another. That's down to the success of the programming.
Of course, it's all what-if scenarios on both sides of the argument though.
I stand by my comments that it is the easy option to chop BBC3. There'd be resistance from political types had they announced BBC4 or BBC Parliament were being ditched.
The BBC's remit is to serve audiences of all ages. We've lost BBC Switch, we're losing BBC Three, so what is there for the massive section of society after CBBC? Are they now expected to stick with BBC Radio 1 or go to ITV2/E4 then?
Why the hell don't they cut BBC Red Button? Smartphones/tablets/internet & connected TV more than cover the clunky, dire and slow Red Button service.
Unless, of course, threatening such an audience directly forces it to become vocal, at which point the channel's detractors are proportionally less powerful. Equally, threatening Six Music was the best PR campaign the channel could have hoped for.
Even down to the channel's clearly planned demise being hinted at weeks before, with the press office giving comments that force the story to live on ('nothing's planned, but it could well happen. Maybe, maybe not. Got that?'), then the decision being leaked in such detail the day before the announcement, then the months of consultations and news reports... It is, actually the best way the BBC has to forge a defence. It can't be accused of not trying to live within its means, or of being aspirations, or of 'living in a bubble', while pushing the external pro-cuts lobby to the side. Young people might not always be politically vocal or powerful, but are the BBC Trust or MPs really likely to ignore potential viral twitter petitions and protests? Perhaps not...