I think the biggest decider of how quickly the world transitions away from Microsoft or Apple, is dependent on how the USA looks within a decade. If fascism in the USA stays strong, it would have knock-on effects with foreign relations. Should the USA pull out of NATO and sides with Russia, that by extension implies that US software could be hostile to European powers. The excel spreadsheet with fiscal data for Polish military expenditures? It might be sent straight to a three-letter agency and shared with Russia. Internal French memos that oppose the US? Leaked. And so on.

That would cause a major shift towards FOSS from governments across the world.