Honestly, when I ordered the car there was no promise of free lifetime supercharging. They added it as a freebie before the car was delivered, so I still feel lucky to have it. The uncorking was another unexpected freebie.
The free lifetime charging is more of a percieved value than a true one. If I drove 10,000 miles a year on trips using superchargers, and if electricity is $0.18 per KWH, and I use 350WH per mile, I'd spend about $630 per year on electricity. 10,000 miles per year is far more than I'll drive on trips. My benefit is probably closer to $200. There are some ignored parameters, the charging isn't 100% efficient, I usually use less than 350WH per mile, etc. still the perceived benefit is far more than the actual cost to Tesla. Tesla gets a lot of press for this. They don't need to spend money on advertising.
If the free lifetime supercharging sells the more expensive cars, I think they would be nuts to scrap it.
If congestion at superchargers is a problem, then they might consider charging owners for supercharger use within 100 miles of the owner's home. That way they could still offer the value of free long distance travel but they'd discourage use of nearby superchargers. Assuming people travel the same amount on long distance trips, they'll be using the superchargers a similar amount whether they pay or not so the congestion issue shouldn't really affected by the long distance travel.
I think the free long distance supercharger use was an absolutely brilliant move on Tesla's part. I'll be surprised if they don't continue it. Discontinuing it and bringing it back gets more press than leaving the program in place, maybe that is part of the plan.
I'd like to keep my car a long time. Our cars are generally 20 years old or so when we replace them. We currently have an '04 Honda and a ‘98 Camry. We still think of the ‘04 Honda as our “new” van. We put about 200,000 miles on them. I do some amateur astronomy, I'd like to put 250,000 miles on the cars. That's the distance to the Moon.
As far as the free supercharging staying with me and not the car, I'd seen it when there wasn't a 2017 deadline, so I'd thought it was lifetime for me with Tesla's. I don't know what they are thinking, are they figuring I'll replace the car within 7 months of buying it? If they initially promised me “lifetime”, I'd expect them to honor it. As a man in his 60's, it is probably moot for me, though, if I keep cars for 20 years, this one will probably see me through.
