From my understanding, the high valuation of Saudi Aramco does not seem to stem from them being the best in to industry for processing oil, but rather, from their access to the richest and cheapest source of oil. This license is their source of making huge profits - i.e. the difference between the cost price versus the market price.
To the best of my understanding, Saudi Aramco has no ownership of the oil fields but merely manages them on behalf of KSA. So is there anything impeding KSA from simply selling oil field access to someone else than Saudi Aramco after the IPO, and in effect, eliminating Saudi Aramco's source of profits?