A rumor by the fairly reliable @ice suggests we may have a repeat of the first half of the year when Samsung hoarded all available supply of Qualcomms top chipset, leaving other makers to search for alternatives (like the 821) or delaying their H1 flagships.
Allegedly, Samsung has done it again and bought up most of the initial batch of Snapdragon 845 chips. Those will be used in the Galaxy S9, specifically the one to be sold in the US. Samsung will have the Exynos 9810 for Europe and Asia, but thats of little consolation to the likes of LG, HTC and Sony (Huawei and Xiaomi do have their own chips, though).
Earlier, Qualcomm selected TSMC over Samsung to fab the Snapdragon 845. Now it seems that this decision wasnt driven by what happened last year – Samsung Semiconductor building Snapdragon 835 chips and sending them to Samsung Electronics, which pushed others to resort to using the older chipset.
Source (in Chinese)