I can’t really answer any of your questions, other than to give you my assumptions based on some personal experience, and some reference to things I have read in this forum. I am not a Blink representative, just a customer, like most everyone else who contributes here.
First, I have just bought a new outdoor camera system and it came with a sync module 2. When I added that sync module 2 to my existing account, it said, and this is not verbatim, but represents the sentiment, ‘Thank you for your custom. As a valued existing customer, you will never be asked for a subscription for any of the XT, XT2, or current generation of indoor and outdoor cameras. Please continue to enjoy your free cloud subscription.’
Clearly, this was deliberately worded to exclude any future products, but for the current range, as an existing customer, you are covered, if my experience is anything to go by. Who knows what the future will bring in terms of additional products, but it’s clear they were excluded from their promise, by referencing only past and current products.
As for enabling the USB port, on the original sync module, I’d be amazed, based on everything we’ve seen in terms of features only being available on current product. Sales is king.