The USA is likely to get the Aramco IPO.

http://www.dailymail.co.uk/news/article-5058061/Saudi-prince-killed-firefight-resisting-arrest.html

This is not an anti-corruption campaign but a power grabbing fight by the crown prince.  He wants to make sure he can stay in power and have absolute power.

I believe the USA will get the Aramco IPO in exchange for Trump's support for the new crown prince.

The real contenders for the Aramco IPO are the USA & HK.  However, the USA will have a higher chance because of political reason.