Democracy in a big country will not work - big as both in terms of territory and population.
The US is a good example - US is declining NOT because it has wasted so much money on too many wars, but because of unmanageable regional interests that tear the country apart.
India is another shining example - still poor and uncivilized.
UK is on its way to be ungovernable.
Democracy in small countries work very well, like Switzerland, Norway, South Korea, because there is no such thing as national politics. All politics are regional, localized.
China can never be governed successfully by multiparty democracy. It will not work. However China can make some reform to allow some freedom on local politics, on the provincial level - that is about as high as it could go.
Democracy is overrated. It is not a magic pill that cures all.