It took China almost 30 years to cultivate economic development zones into the logistics chain to build the first iPhone. That kind of development can't be replicated in a few years, is likely out of reach for smaller nations (read anyone except India) or viable in a geographically distributed fashion. The problem isn't just moving factories but have a geographically centralized logistics chain where thousands of components are within hours of each other, supported by millions of specialized high skill labor, preferably with similar language proficiency, where new production can be rapidly iterated to meet market demands. A "small" country with 100 million people are not going train a large proportion off their entire population to fill football fields with tooling engineers and other specialists. It's just not demographically in their cards. And it's that level of centralized scale that enables China to manufacture high end electronics in the timescales that modern business cycles require.

That's why all the outsourced electronics production so far are low end assembly in countries adjacent to China where components made in China (other than very high end IC) can be quickly shipped to them have locals can be trained to assemble processes that has been matured and figured out in China. If all Chinese manufacturing magically shifted across ASEAN countries, I don't think there would be the collective capability to organize logistically to produce and iterate a new annual Apple product launch - the entire Tim Cook screw anecdote. The nature of manufacturing has changed. Maybe India can replicate that, they are not starting from zero, but I don't know if Indian democracy can make the extremely unpopular changes Chinese state directed capitalism / SEZ went through. This isn't an issue that can be solved by funneling money / FDI, these things take much longer time than a few years and still can't replicate the advantages of Chinese scale on things where scale matters. There's a qualitative difference in different governance models ability to execute policy and realize capabilities. Distributing Chinese manufacturing among bunch of competing countries with inevitably expensive and inefficient physical and regulatory interconnects just won't produce the same capabilities.

Even if we ignore the fact that countries like Vietnam are reaching infrastructure and labour limits, i.e. they literally at land, road, port, worker capacity which will optimistically take decades to cultivate - generations in terms of expertise that can't be rushed. Or that a lot of the factories that moved out of China are Chinese owned so money and control is still tied to CPC. Or China might undercut ASEAN by setting up parallel manufacturing in Chinese influenced Africa. There's still the matter of automation. Shorterm, China is targeting to increase automation from 68 industrial robots per 10,000 employees (14th in the world) to 150/10,000 employees (9th). For reference, top4 is Korea 631 /Singapore 488 / Germany 309 / Japan 303. China is not stopping at 150 long term, their poor demographics lack of youth due to family planning means labour heavy manufacturing is on the way out, but automation will potentially enable China to retain all their manufacturing advantages in terms of logistics and expertise in long run. And once China learns to make advanced integrated circuits and airplane engines, maybe software, they'll more or less have no western dependencies.