this seems to be a visualization of data already present in the logs (behind some labs addon IIRC), but while useful it's a far cry from what new relic does (i.e. insights into _what_ is taking time and why, not just how much/when).
The Metrics displayed in the new Dashboard focus on the characteristics of app execution on Heroku, rather than internal instrumentation of the application. Hopefully that's useful in providing more visibility into tuning applications on the platform.
If they acquired New Relic and integrated it into the Heroku Dashboard it would give them another edge over normal hosting, but doubt that will happen. New Relic seems to do fine be themself.
New Relic is a bigger business now* (*speculating). And it used to be integrated into the dashboard before the add-on marketplace existed.
Heroku is owned by Salesforce so I doubt that. Interesting to know it used to integrate directly into Heroku before the addons though, didnt know that.