There is now substantial evidence that the development of next generation of Yaris is in full swing. The current generation came out in 2013 which is a long time for one generation in such a hotly contested segment, so this is welcome news.
Next gen will be underpinned by the DNGA platform (lower cost version of TNGA) currently used by Daihatsu rocky/Toyota Raize. This is because Toyota has delegated development of ASEAN version of Yaris to Daihatsu/Perodua.
Sources of Filipino website Autoindustriya say that it will be launched in August next year and a new hybrid version will launch in 2023 (with possibly the same setup as Aqua). There is also speculation that it could be a 1.2 mild hybrid system along with 1.0 turbo and 1.5NA options.
In Pakistan, current generation of Yaris is around 1.5 years old so IMC will want to continue with it for a while. Next gen Yaris will probably not come to Pakistan before 2024-25. But when it eventually does launch, it should be a relatively smooth and quick process since IMC will already be using TNGA platform for Corolla and Corolla cross (and probably even next gen Hilux/Fortuner).
https://www.autoindustriya.com/auto-industry-news/insider-all-new-toyota-vios-for-q3-2022-hybrid-in-2023.html