In theory, that is what you want but in reality, this scenario seldom happens. You get what you paid for especially in advanced nodes, TSMC is only foundry who has alomost everything what you need. Others you have to know how to play/work together. Otherwise you will be very disappointed.
I might agree that it is primarily a signal to TSMC but only time will tell. It must be difficult for Qualcomm to be wafer constrained given the overall economy and the loss of shipment opportunity. Perhaps, TSMC will get the message and provide an increase in wafers to placate Qualcomm. I still think that it makes sense to ensure alternate sources both as a way to keep suppliers interested and as a hedge against natural disasters.
This is very good news for UMC. UMC had a very bad 1st quarter because its first-Quarter Net Profit was Down 70%. After looking at the recent developments that have taken place looks like UMC is on storng recovey path.