More to the point, even if we grant that the PRC won't invade Hong Kong the moment Britain unilaterally extends the lease- a highly doubtful proposition- as soon as 1997 comes around, the PLA will simply occupy the New Territories as it is legally allowed to do. It will then turn off Hong Kong's water and power.
Of course, given that there are no circumstances under which even Britain's allies would support its violation of international law by tearing up the Treaty of Tientsin, the PLA would simply occupy the city. Britain can't abandon the treaty without throwing every single one of its other international commitments into serious question. It would panic the stock market (already spooked by an entirely avoidable war in Asia's financial capital, sparked by Britain), embarrass and anger British allies, delight British enemies, and probably cause the immediate fall of the government once the public is told that they're risking a nuclear war over a completely indefensible city with very few white people in it.
By 1949, Britain cannot hold Hong Kong, or turn it over to Taiwan.
Of course, given that there are no circumstances under which even Britain's allies would support its violation of international law by tearing up the Treaty of Tientsin, the PLA would simply occupy the city. Britain can't abandon the treaty without throwing every single one of its other international commitments into serious question. It would panic the stock market (already spooked by an entirely avoidable war in Asia's financial capital, sparked by Britain), embarrass and anger British allies, delight British enemies, and probably cause the immediate fall of the government once the public is told that they're risking a nuclear war over a completely indefensible city with very few white people in it.
By 1949, Britain cannot hold Hong Kong, or turn it over to Taiwan.