Yields in DRAM and other Massively Redundant Processes
No manufacturer will ever release yield data unless they have to for some reason. It's considered a trade secret. So- to answer your question directly, no- it isn't advertised in the industry.

However, there are many engineers whose jobs are to improve the line throughput and end-of-line yield. This often consists of using techniques like binning and block redundancy to make losses off the line function enough to be saleable. Block redundancy is certainly used today. It's pretty easy to analyze:

(failed blocks per part)/(blocks per part)*(failed blocks per part)/(blocks per part)

That'll get you the probability of both parallel blocks failing. I'd doubt you'd end up with a yield as low as 70%, as typically 90% is the minimum acceptable yield.