The odds are it will be the latter, only $70/year isn't quite up to Microsoft's standards. That's the price for a single-user 365 subscription, with a multi-user one running $100/year.It's way way way better, as long as periodic update dont cost the price of a game. And that's where the problem lies really.
Let's take FH for example, since FH3, they all feel like update of it for me, so having to just buy FH and then the car I want with dlc isnt bad as long as dlc are price correctly. If they release a game pass each year worth around 70 usd, there's no point really, it would be the same thing.