I think it is less about not having an extradition treaty as it is just living in a country that doesn't really actively search for people needing extradition. as long as you have good paperwork for wherever you live and stay the hell off the radar of local authorities, you could probably do okay in lots of central/south american countries. avoid europe and all of their nanny cams with facial recognition. avoid getting online with your old persona's credentials and visiting old family/friends. could probably do pretty well

Something I've always sort of wondered: If you live on a yacht in international waters, will the US Navy come and pick you up? For someone of Ms. Holmes' level of GTA stars.

There are a lot of unrecognized territories in the world. Wa State, Western Sahara, Rojava, Palestine, Transnistria (remember hacker weev?), Ambazonia, Artsakh, wide swaths of factions in central Africa. It's impractical to extradite people from these regions, although perhaps if they're badly enough wanted the CIA can toss them in a bag and just straight up drive them out or bribe others to do same.

It's thought for instance intelligence may know wanted British terrorist Samantha Lewthwaite is in Kenya or Somalia, but impractical to extract due to being controlled by Al-Shebab. Nobody is gonna send the troops/3 letter goons into some no-mans contested land over some non-violent holmes like character.