Matt George over on the Map Viewer Beta forum, Russell Roberts is indicating that cluster labeling isn't planned? Will someone please calm my nerves? I've been flipping tables all weekend long. No way in banana republic you can not add labels for clustering at some point.
One other thought - I'd question why one might prioritize the ability to query a cluster or access it in Arcade over the most basic functionality of labeling the cluster. Arcade I kinda get because if I could just write an Arcade expression to cluster and label my point features, that'd be just fine with me.
As for the querying of a cluster I mean, it sounds cool and useful and I get it if you need that capability in order to label the cluster in the first place, but I don't think that's the case because it that functionality already exists in one state or another given that currently you can get the cluster feature count in the cluster's popup. We just don't want to have to click on the cluster to read the count out of a popup, that's all.
Look guys, it's like a chocolate chip cookie. Right now, you're giving me a cookie (the cluster) and a bag of chocolate chips (the counts for each cluster). For a while, I was fine just popping a a chocolate chip into my mouth with every bite of cookie but at this point, getting annoyed. I don't want to have to grab a chocolate chip out of the bag with every bite of cookie (analogous to clicking on the popup to see the cluster count).
We have the cookies (clusters)!
We have the chocolate chips (cluster counts)!
Take the chocolate chips out of the bag (the popup) and just bake them into the cookies so I get all that goodness in every bite.