I'm not sure why you still believe this to be true when there are reports of Trump considering an executive order that would effectively ban Chinese network equipment from the US on the grounds of national security. National security is sufficient legal justification for any mercantilist American policy, whether it be tariffs or outright sanctions.I don't see the chip level part happening, as Huawei is not blocked for example, selling tablets in the US market that uses Kirin chips.
One of the best Android tablets in the market, great for gaming and video watching.
Theoretically if phones using Kirin chips are going to be blocked from the US market or some other market, it would have to be done in the commercial level, meaning a company like Qualcomm would have to sue Huawei for patent infringement on those chips, and Qualcomm would need to succeed in those case. If Qualcomm could have done that, they would have done this years ago against Huawei phones directly, but Huawei and Qualcomm could already have settled on a cross licensing deal.
A more immediate issue is that how phones without non Qualcomm chips can be vulnerable to patent troll companies in the US. Qualcomm as you see is acting as a sort of patent protection "godfather" from tech patent trolls, which is needed by companies with weak patent portfolios to defend themselves. Huawei has a huge patent portfolio that is ready to go to war --- hence it was able to stave off lawsuits against it by other companies --- but companies like Xiaomi may not. To get a phone like the Poco F1 to the US market, patent umbrella is needed and this is why Xiaomi took so long to get to the US market.
If the US made it so that only Android smartphones with Qualcomm chips can be sold in the US excluding other chips, then they are setting up Qualcomm to become a monopoly, and that would be a big loss for the US market. The US government is in fact, investigating if Qualcomm is acting like a monopoly and is doing monopoly like abuses.
But as we know, the US market isn't the only smartphone market in the world, and you really should not be hampered selling Kirin powered phones from India to Indonesia to Rio de Janeiro and Timbuktu.