I would think that would set a good precedent which could encourage people like Kim Jong Un or Bashar Al Assad to consider that as an option, but the closest example I can think of is Pinochet, who was eventually prosecuted. Maybe Mobutu, but he died very shortly after his exile.
Alternatively, do any of the children of such dictators continue to live affluently off of the alleged proceeds of their parent's graft, free and clear so to speak... without threat of prosecution or civil forfeiture themselves.
I think President Soeharto of Indonesia fits your bill quite well. He is the second president of the Republic of Indonesia.
The legacy of his presidency is under debate even today. Some of his economic reforms and infrastructure projects helped make Indonesia one of the fastest growing economies in the world up until the 1990s. He transformed the Indonesian government into a strong, centralised unit that 'worked closely' with the military. His presidency saw the levels of poverty and illiteracy fall drastically.
But, he also filled the ranks of the government with his military friends and relatives. Lucrative government projects would be assigned very often to his relatives. A select few people could own many businesses which were often assigned generous concessions and insurance through public funds. He used anti-communism sentiments to invade East Timor and many people died there until Indonesia pulled out many years later. He was quite draconian even on student protestors in Indonesia, even in the capital.
To get a small idea of the level of corruption, check out this New York Times article from 1998 after his resignation:
And yes, he did resign. But not without a fight. The 1997 Asian Moneyray Crisis hit Indonesia very hard with the exchange rate going from Rp. 2,000 to the USD to nearly Rp. 17,000 to the dollar. He still held on until the protests led to mass riots with local populations assaulting ethnic Chinese citizens and foreigners. I was about 3 years old at the time, so my memory is dim. But I distinctly remember the company my father worked for ( an Indian textile company) bussing an entire colony of Indian citizens ( around 400 of us) to an expensive hotel near the colony and then flying us back to India the very next day. This happened all across Indonesia. Really, he didn't have a choice but to resign.
Post-resignation Soeharto lived quietly in his home. Multiple efforts to prosecute him have been tried until 2008 when he died, but each time his family doctors offered mysterious health problems that prevented him from being present in court to be tried.
His family has been fending off anti-corruption charges ever since. To this day they have wide support in the Indonesian Army and among anti-communist parties. The true amount of wealth controlled by the Government is unclear. But it must be vast. They still live in much more comfort than most people worldwide, let alone In Indonesia, can afford.
His son was tried and sentenced to jail. No other convictions have taken place. Since his death, the general mood in Indonesia seems to be to celebrate his legacy and his achievements rather than condemn his horrible human rights record. It is a tough debate to be fair.
As for whether this can help with removing Kim-Jong Un, I'd be sceptical. The Indonesian public's fury at Soeharto was what led to his resignation. In North Korea, despite a horrifying famine that had people resort to cannibalism to survive and terrible conditions of poverty and fear and state control, opposition is still only bubbling quietly, not furiously revolting to pull him down. There are not many more sanctions that can be placed on NK.
Best I can do is Daniel Ortega, leader of the Nicaraguan Sandinistas and effectively the leader of the country from 1981-1984 and then officially the president from 1984-1990. You may remember the Sandinistas were targeted by the US government in the 80s as part of the Iran-Contra affair because they were dirty commies. During his tenure with the Sandinistas from '79 to '90 they did some pretty bad things, violating civil rights and doing a bit of ethnic cleansing on the indigenous population (on the order of thousands of people), but he was never prosecuted for any of this. As far as personal enrichment goes I have no idea
In 1990 he agreed to democratic elections, lost, lost again in '96 and '01, then was elected in '06 and again in '11 and a third term last year. International commissions have (when allowed to monitor them) seen Nicaraguan elections as being above board so he is probably a legitimate ruler now, but he is more moderate than back in the day when he helped rob a bank with a machine gun. He did get prosecuted for that, was jailed, but was released in the mid 70s and that was the last time he was behind bars