"Look at the BBC1 Saturday night schedule - hardly 'minority interest', is it? "
Before I start, I'm actually not in favour of the abolition of the BBC, although in my darker moments I think a subscription service which offered Radio 3, Radio 4 and BBC4 (called, perhaps "BBC Waitrose") would be something I'd rather pay £150 for than the current service.
But BBC1's primetime output is the worst possible argument for the existence of the BBC. It's indistinguishable from ITV, which manages to function happily (-ish) on advertising revenue.
The argument for the BBC is the programmes that can't be funded by mass-market advertising. The moral conundrum, see also the Arts Council, is whether it's acceptable to impose a mass tax in exchange for niche content. The BBC's response to that is to make some non-niche programmes, and trumpet that you can watch mass-market pap on BBC as well as on ITV. I think they'd be better off finding everyone a niche, so everyone can feel that they're getting something a little special for their license fee, but that's probably why I'm not a channel controller.
For people who watch mostly BBC1, they'd see very little change if the BBC became a commercial or subscription offer. The problem for people who, like me when I'm being wistful, want essentially a British HBO, is that a small percentage of the US population is larger than the same percentage of the UK population, and the costs of quality TV don't scale with audience size. If you imagine a UK-HBO, they would have less than a quarter of the money, all other things being equal, and could therefore either make a quarter of the programmes (ie, not enough to make people want to pay) or spend a quarter on each hour (ditto). BBC4 has so few viewers that as a subscription channel, it would be able to show little more than the test card and old episodes of Top of the Pops; it would, in fact, look like that post-apocalyptic game show on Mitchell and Webb, without the HD sheen. It's the difference between a country of 65m and a country of 250m.
The subscription model works well in very large populations (ie, HBO in the USA) or for things that are very popular (ie, football
). Sky works as a subscription channel as there are enough people willing to pay for Premiership football, and everything else rides on the back of that cash cow. It won't, sadly, work for niche programming in the UK.