The root of corruption in China lies in the inconsistency between its political system and  its mixed economy  that  consists of both marketing economy and state capitalism.  This inconsistency  did not exist in Mao era, nor in any other big country,  

For example,  those countless economic projects,  which were monopolized by certain state-owned enterprises,  now are open for bidding.  It opens a lot of loopholes for those who have granted power and privileges to have a say in deciding the biddings.  The current system cannot guarantee they are effectively supervised.

If Xi could  not find a way to resolve this inconsistency fundamentally,  his anti-corruption struggle is not optimistic about the future.