All the features can be released as software update, even the BLE functionality. The older unit uses nRF52832 that supports BLE...
Actually, two new Varia radars were just announced this morning. https://www.dcrainmaker.com/2020/05/garmin-rtl515-rvr315-cycling-radar-review.html
Hoping that the "peloton mode" will be in an software update for the 510...possible, isn't it?
What would you like in a new version? My RTL510 is perfect as is.