Without any prior changes, then it would be the early 1980s. Rhodesia was running severely low on oil, and that was before 1/4 of it was destroyed in
a 1978 ZANLA raid on a fuel depot in Salisbury, after about 1982, Rhodesia could no longer afford the war and would be forced to launch a counter insurgency, which would turn every Rhodesian city into a warzone.
A lot of the failures of Rhodesia came down the early behaviour of Ian Smith, he was profoundly anti-decolonisation and the UDI was a national suicide, Rhodesia should instead have demanded dominionship or even integration into the UK. NATO would've been more likely to support Rhodesia if the
Vickers Viscounts were shot down in 1968 instead of 1978, and the efforts of ZANLA more intense. Another error was in the military, which was overfunded and ended up leaving Zimbabwe bankrupt from birth, if he used the police to tackle raids, then there would've been less fear in African communities. Another error was by entering other countries, a large portion of Rhodesia's neighbours wanted to recognise the quasi-terrorist state for its exports, but raids into the ambivalent nations of Zambia and Botswana kept them from supporting them and led to people from those countries joining in the war, this strategy also inflamed tensions in Mozambique. If Smith stayed in the union, ended racially separated voting rolls, focused more on economic growth than military crackdowns, didn't censor the press and gently pivoted for independence, we could see Rhodesia on Google Maps.