Hi,
The TX1/TX2 hardware is capable of streaming 6 cameras in parallel. There are some minor differences in the driver level between the TX1 and TX2. Hopefully you do not have to worry much about the platform side driver as Nvidia maintains and fixes bugs in their L4T releases. However the sensor driver is your responsibility and would require minor changes to work on TX2.
The main difference I can think of between TX1 and TX2 is the change from Kernel version 3.10 to 4.4. Hope this helps.