Long past the time many had ceased caring, Sarah Palin announced on Wednesday night that she was not running for the presidency in 2012. Fox News alone of America's cable networks thought her announcement was more significant than the death of Steve Jobs. Everyone else reacted with a quick shrug and moved on.

It had become obvious that Palin was not going to be a candidate. The reality is that Palin didn't stand a chance, so badly has she squandered her political capital within the Republican party over the past year with cheap stunts, such as an on-again, off-again grandiose national bus tour. Her career in national politics as a candidate is over.

The most straight-forward implication of Palin's decision – along with the announcement by New Jersey governor Chris Christie that he would not be running – is that the Republican field is set. There is now no prince across the water. That means Republican voters will either have to come to terms with Mitt Romney or the alternative, most likely Rick Perry.

But for Palin and her supporters, the announcement ends any serious opportunity Palin may have had. The weakness of the 2012 Republican field was such that had Palin chosen to make a serious effort, she could have done well. She could have won the nomination. Now she almost certainly never will.

Even if Republicans don't regain the White House in 2012, the GOP has a rich crop of potential candidates in 2016: Christie, Perry, Marco Rubio, Jeb Bush, Scott Walker. By 2020, Palin will be a distant memory, just as if Al Gore was running for the Democratic nomination in 2012.

In reality Palin's career was effectively killed off when she decided to quit midway through her term as governor of Alaska back in 2009. From that moment on her unfavourability ratings climbed to toxic levels. When the Tea Party movement arose she quickly embraced it, backing herself further into a shrill corner of the Republican party, speaking in the code of talk radio and appealing to an ever-shrinking fan base.

What beckons instead is a career as a political quasi-celebrity on the conservative right, alongside the Oliver Norths, Ann Coulters and J Gordon Liddys. But without the attraction of being a potential presidential candidate, Palin will find the spotlight and the crowds have moved on.

Over on her supporters' websites, there is much gnashing of teeth and a good deal of denial. No wonder, because only a week ago her supporters were being solicited for donations to help convince Sarah to run.

On Mark Levin's radio show, where she made her announcement, Palin was full of perky plans for helping elect conservatives in 2012. Like a Broadway show that lost an audience, she plans a tour of the provinces.

Many Republicans will be glad to see her go since she drives away the moderates and independents that the GOP needs to win over to hold the White House. In a memorable recent blog, RedState's Erick Erickson described Palin's cult-like supporters as "unhinged" and saying of Palin's prevarication: "Enough is enough".

Finally, it was.