A lot of this is not that uncommon for other car manufacturers as well. The "Premium" warranty of a used BMW also depends on the car being serviced at an authorised repairer. Yes, it's the manufacturer trying to be more of an "integrated" service provider and keeping the resale value up, but it also ends when the car gets older. Most of those cars the go on to lead a long life with aftermarket parts and repairs.
I think the question is how practical third-party service will be (by individuals or independent garages). As you suggest, the common wisdom that I've always heard is that, if you want to hold onto a luxury car past the warranty/extended warranty timeframe, that's great and can be a fun and cost-effective auto--but only if you're handy and willing to spend the time or have an indie mechanic who you trust. Otherwise, dealer service will eat you alive.
