The PCA9615 "can" use up to 160mA to drive the twisted pair. But it probably uses just a few milliamps.
The MPU-6050 uses almost nothing. The BNO055 is something special because there is a processor inside, that processor uses current.
All your sensors are 3.3V and the Arduino Mega is a big 5V board.
The MKR Zero is a good choice. Don't buy the Due.
A picture of where everything is with distances would be very helpful !