> Google uses Spanner in-house extensively

True

> it is likely to be available for a good long time.

Where does this conclusion come from?

The google mapreduce paper was released in 2004. [0]

"By 2014, Google was no longer using MapReduce as their primary Big Data processing model" [1]

The google spanner paper was released in 2012.

If spanner lives as long as mapreduce it will be largely replaced in 5 years.

[0] https://research.google.com/archive/mapreduce.html

[1] http://www.datacenterknowledge.com/archives/2014/06/25/googl...