Okay, season 8 seems to be a save bet. But what about after that? What minimum overall ratings does Dr. Who need for not beeing subject for "consideration for cancelation"?
Who knows? It isn't just about ratings. The BBC has cancelled successful series before simply because it's felt a show's gone as far as it can. There's also the cost of producing it to consider. Even if it continues to pull in 7/8 million viewers each week, if it's felt the cost of producing it is prohibitive then it might be cancelled. I think it’s unlikely whilst it’s still successful but you never know. My rough guess would be that if it dropped below 5mil (after time shift/iPlayer etc.) consistently it might be in trouble.
My understanding of the UK ratings system is that anything over 5 million is considered a smash hit. With the latest season of Doctor Who averaging around 6 million, it doesn't have to worry about cancellation.
It doesn't hurt that it's the top rated program on BBC America, and the ratings are phenominal worldwide. That brings in even more money for the BBC. As does sales of DVDs and other related merchandise, as mentioned already.
The usual reason for ending long-running shows is increasing costs due to actors renegotiating salaries. Doctor Who doesn't really have that problem.
The BBC likes to say that all of its shows are funded by the TV license fee, but Doctor Who makes enough money for BBC Worldwide in DVD sales and overseas broadcast rights to cover its own budget and then some. Even if only 100 people watched the original broadcast, they would still make Doctor Who, as long as the money is still flowing in.
Once you exclude major sporting events, the soaps and the reality shows, very few shows out perform DW on any channel.
Ah, no. That would be a breach of the BBC Charter. The BBC is, by Royal Charter, only allowed to make programmes for the domestic (licence fee-paying) audience. If those programmes can then be sold overseas (or to repeat stations, or DVD, but the rule predates any inkling that they might ever exist) and the money spent on making more programmes for the domestic audience, then that's OK and a nice bonus. But making a programme purely or even primarily to make profits from sales (even if that money is then used to make programmes for the UK audience) is out. Banned. Verboten. Breach of Royal Charter leading to continued operation of the BBC being technically speaking illegal (and as we're talking about a Royal Charter, possibly treason ). That sort of thing. It might sound mad - it certainly did back in the mid-1980s when the BBC claimed it was postponing season 23 to save money even though, as Douglas Adams pointed out, it earned more from sales than it cost to make - but the point is that the BBC shouldn't consider profits from sales when deciding what to make, only whether this is a programme the licence fee payers deserve to have. Otherwise it might end up like any normal profit-making TV company, making stuff just because it hopes it'll make money. PS: On Wormhole's point, bear in mind that a 6 million audience in the UK is roughly the same as a 30 million audience in the States, population for population. How many current US series could match that?
A tricky question... World Service is run by the BBC, but until recently was funded by the Foreign Office, not out of the licence fee (I think that might date back to the very early days when the BBC was still a private company, which the government paid to run an overseas service, but I might be wrong about that. The private British Broadcasting Company became the Royal-chartered British Broadcasting Corporation in 1926). Anyway, cutbacks by the current government after they took office back in 2010 changed that, so from now on World Service is funded from the licence fee like the rest of the Beeb (though we may currently be in a transition period - I'd have to check when it actually takes effect).
Gut instinct and anecdotal information alone, I'd say I'm not sure anything outside of Super Bowl, World Series, Olympics, etc, can still garner 30 Million American viewers, especially not on a weekly basis. Does Monday Night Football still get 30Mil+?
Monday Night Football is on ESPN these days, so, no. But Sunday Night Football on NBC was the top-rated show on all of TV last year, and it averaged a bit over 20 million viewers. (Before that the consistent winner for several years was American Idol. NCIS was the top-rated non-reality show last year.) Proportionally speaking, US TV audiences are more fragmented these days than those in the UK.