the odds of hashing a block with positive luck is exactly 50%
No, it's more like 63%. Because the longer-than-average time is unbounded.
the queue will only shrink due to payment limit shenanigans or manual payouts.
Or transaction fees.
Also it is fun to note that in with the last 2 blocks the queue increased another 6BTC with "bad luck"
Uh, bad luck shouldn't increase the queue length.