Look at this "reliable manufacturer" on the site for the presence of STM32F103Vx. They are gone, only small remnants in the sellers warehouses are shown.
And had STM given any guarantees on long-term availability of that part which they subsequently forgot about? I guess not. STM is obviously a reputable and reliable manufacturer, but that does not mean that they will never discontinue a part...
If long-term availability is important to you, base your design on parts with guaranteed long-term availability. All major manufacturer have these series, often designated "for automotive use". STM guarantees 10 or 15 years of availability for these, from the date of market introduction.