Have come across references to this a few times recently & am curious
enough to ask the development community whether the NoSQL movement
holds any relevance for Koha's future.

According to that font of universal wisdom, Wikipedia, "Typical modern
relational databases have shown poor performance on data-intensive
applications including indexing a large number of documents [= any
ILS?], serving pages on high-traffic websites and delivering streaming
media. They can be efficient only when they are tuned either for small
but frequent read/write transactions or for large batch transactions
with rare write accesses, while there are demands for the data stores
capable of heavy workloads with frequent updates."

Thoughts? How wedded is Koha to SQL in the long run?