Blynk 2.0 Arduino USB device always offline

Not really sure what that means.
The idea behind those line of code is to create an additional serial port that can be used to view the debug serial output from the device (which can’t be done via the regular serial port, as it’s being used for your Blynk connection).
To view this you need an FTDI adapter, and you would also need to decrease the baud rate of that SoftwareSerial port, as you hardware isn’t powerful enough to simulate a serial port using software with baud rates any higher than 9600 baud.

More info here…

Without sight of that debug serial data it’s difficult to know what’s happening.

I would suggest changing the port to 80 rather than 8080 though.

Pete.