Hello @kumardeo and sorry for the delay. We have not committed to a firm schedule yet, but there are plans to offer the 3.x core in the coming months! We need to tread carefully to avoid suddenly breaking everyone's sketches 
Unofficially, you definitely should be able to use any Espressif 3.x core (*) on the Nano ESP32. Also, feel free to report any problems you have with those here, so that we can help and investigate!
(*) Except 3.2. There is currently an issue when building that specific version with the Arduino pin mapping, but the fix has already been accepted and the next release will again work.