If they actually can increase the concurrency now, that's good news!
We asked for that as well, and at first the support said they did that, but turns out they increased the Athena queue length instead of concurrency - so the queries wouldn't fail (until the queue is full, anyway) but the throughput was still the same.
Then the team of AWS account managers and solutions architects (who assured us many times that the concurrency can be increased) get into a email discussion with the support and Athena team, before coming back and telling us it cannot be increased. No apology or anything. Recommended us to run Presto on EMR instead.
We asked for that as well, and at first the support said they did that, but turns out they increased the Athena queue length instead of concurrency - so the queries wouldn't fail (until the queue is full, anyway) but the throughput was still the same.
Then the team of AWS account managers and solutions architects (who assured us many times that the concurrency can be increased) get into a email discussion with the support and Athena team, before coming back and telling us it cannot be increased. No apology or anything. Recommended us to run Presto on EMR instead.
It was a sobering experience in how AWS operates.