On Sep 21st Quake Live had a record 6K simultaneous players join from Steam, that was the peak.
Last Sunday the number crested at 2.4K
Looking at the excellent graphs provided by Steam, we can note a gentle, but consistent, downward trend. Quake-live on Steam is experiencing a net-loss of a few players every day.

Personally I welcome the trend as I have lost all faith in the current custodians of QuakeLive. There is no indication that SyncError/ZeniMax has the courage to admit to any missteps.
The last two updates were simply bizarre. They needlessly discontinued a product that had an established customer base (classic) and replaced it with a new product (QL with Loadouts) for a hypothetical future customer base. Well we can’t say they didn’t commit to the idea.

This move did not strike me as a New-Coke fiasco, but more of a last ditch panic initiative to magically boost revenue.

Now the money is spent, the new product is on the shelf, and I’ll bet it’s not generating anything close to their forecast. In retrospect it would probably have been cheaper to burn the money.

So what happens next?
ZeniMax does not appear content maintaining QL as a hobby, but also can’t make it profitable (or at least cost-neutral).
Hopefully they’ll sell QL. Maybe a new owner and a new development team can keep this game alive for a few more years.