I think it was pretty silly to announce the Plaid+ a year out and describe it so specifically, particularly WRT to 520 miles of range. All you're doing is setting tough expectations and constraining yourself. I doubt the range part is "cancelled," but when it arrives was probably subject to the Elon factor, and the realized they were just boxing themselves in. The 520 mile range and structural battery pack is probably in the cards in the future, but as to when who knows.
Also, WRT range, people are expressing all sorts of opinions here, so here's mine: if your car has a maximum range that is greater than or equivalent to the maximum amount you can drive it in a day, you're probably good, as long as your destination has the infrastructure to charge your car overnight. I tend to top out at 500 in a day, so a car that can support that without meaningful battery degradation would do the trick for me. At that point the argument for ICE just withers up and dies.
So say you only get 80% of your rated range of 500 and further say you're only willing to consume 90% of that range at a time for battery preservation. That's 500/.8/.9= about 694 of rated range. I bet we see that in 5 years. And every range increase along the way will be welcome.