Be aware that if you purchase the "extended warranty" (really a misnomer as it's a contract to repair items and not a legal warranty), you MUST have Tesla do its $600 (or discounted, in the case of the prepaid maintenance) service EVERY 12,500 miles or once a year, WHICHEVER COMES FIRST.
The standard 50,000 mile warranty also states that in order for the warranty to be valid, the car must be serviced according to Tesla's recommendations. Tesla's recommendations are every year or 12,500 miles, whichever occurs first, per the owner's manual. So even with the standard warranty, which you say is immune to the service intervals, states in writing that you must adhere to Tesla's recommendations. Yet Tesla still does warranty work on my car even though I don't adhere to their stated recommendations.
Those driving the car more than 12,500 miles will not have the full 4 or 8 years, as the 12,500 mile interval will come back and bite later.
So, to recap: First 50,000 miles/4 years is covered under a warranty. You do not need to take your MS to maintenance services at 12,500 miles or one year to keep this factory warranty in place. But those who bought the extended warranty (or those who buy it prior to expiration of the original warranty) must be aware that it's not worth the paper it's written on unless you have always abided to the 12,000mile interval.
Be informed consumers.