Well, we'll have to see what the plans actually shake out to be, this is just a notice that renewals for customer-paid accounts are no longer in effect.
It does say they are working on a technical upgrade for customers. BMW still has a bunch of effected vehicles still under warranty and CPO which are entitled to BMW Assist services as part of the new vehicle/CPO vehicle purchase that they still need to provide service to.
They are stopping renewals because owners outside of the 4yr (for new vehicles) and 6yr for (CPO vehicles) are only permitted to renew yearly.
What they have been moving to with the 2014+ ConnectedDrive vehicles is no longer packaging services into large packages (Safety and Convenience) and allowing customers to purchase only the services they want. Now whether or not this works out to be cheaper for the owner or not remains to be seen.
Now I do see them phasing out the old TCU-based vehicles completely as they were mostly CDMA or basic GSM devices and most cellular providers are phasing out those networks. I would suspect that the "technical upgrade" they are referring to would only apply for Combox-enabled vehicles (03/2010 builds and up).
Otherwise, it does leave a space for third-party suppliers to fill in the gap. BimmerRetrofit already is beta testing a service for the NBT-based vehicles which provides some BMW Assist services via a customer provided SIM. They've posted about it
here.