I doubt it will mean much. The core benefit of Privium is the priority access, but on the other hand if Amex downgraded Privium to only basic one, that would anger quite a bit of their userbase. Also, Amex lounge will be non-Schengen, so not particularly useful for lot of the travel.
I wonder if they could negotiate with Privium a sort of in-between tier which would exclude Privium West lounge. But that might be more trouble than it's worth.