So this is something like mtail [1], with the ability to also drill down into the raw logs, and integrated into Grafana? Sounds great!
We're heavy users of Grafana, Graphite, Prometheus, and Elasticsearch, and while the latter started in a BI role it's expanded to take on pretty much anything we can throw at it. However, there's still tons of system and service logs we're not gathering yet, because the effort to get them to Elasticsearch and store/maintain them is not worth it, especially since the value is not always clear until well after the pipeline is set up.
I'm definitely excited to see what loki can do for us, and just upgraded one of our test Grafanas to nightly to start playing with Explore, looks great!