Sadly,money always talks and Bernie wont stop comparing Turkey to richer countries.
Simple solution. Get more folk to go, make the event more finacially viable and the race will be saved. Hardly MrE's fault at all.
I never say this is ALL Ecclestone's fault.Some fans here make me mad because they do support F1,they do have enough money but they say:'I can watch it on TV,if i go to istanbul park i cant see majority of the race,plus the traffic and hot weather.And i am going to pay for that!' I cant understand them.But also there are people with not much money but they collect some for going to that race.I have met many of them.
People in charge of this dont make so many ads that may be another reason too.If Turkish GP was going to stay i would persuade my f1 follower friends to come and i would complain to this people in charge of the organization about the ads.But unfortunately theres no use of doing this 
F1 is a business that can't be subsidizing an unpopular sport. Turkey only gets around 36,000 fans for the whole weekend, hardly enough to pay for the celebritory champagne. If the Turks won't support F1 why should anyone else support F1 for them?
No,actually there where more than 150,000 people this year.This was reported.But still not enough,some people cant afford the accommadation and flight pay because most fans live away from Istanbul.
You make a good point. I believe the locations where motorsport has a very rich history will do very well. What Bernie is doing, which does have good intentions (spreading F1 to other countries) but also carries huge cons - is to take F1 where money is, unfortunately, where there's money doesn't mean there is rich racing heritage.
Myself for example, I attended the Msian GP thrice..and I'll never go again. Simply put, 1st time I went for the experience, 2nd I had great tickets for the grandstand (experience), 3rd, I was just bored and missed by TV. You don't get the whole 'story' of the race by going to the GP, and I will never attend the Msian GP again. Other countries, lets say where there's rich heritage like Italy, GB, Monaco, hell yeah! (again for experience)
New circuits are like cars, they 'depreciate' after a while. When racing isn't embedded in the culture of the people, they don't see the point to go for a while. I love racing, but seriously...the people at the race track are boring corporate clowns who attend for the sake of attending. The best people are on the hills - not much money, but plenty of passion. However, locals do get bored after a while...most races especially in Asia will have to depend on new target markets - and they aren't easy to find.