Bubble memories. DRAM wiped them out. Actually, IIRC they were non-volatile, so other NV memories wiped them out. Bubble memories never achieved high-volume manufacturing and were overtaken and surpassed by modern IC technologies.
The real point of this thread is that despite all the controversy the transistor is not the radical departure form tubes that many argue it to be.
Even more thrilling is the notion that the CD was invented by an audiophile disgruntled by vinyl. Yes he applied for a patent. More on that later.