For those in states where Tesla has been able to do direct sales, I can assure you, after purchasing 3 Tesla vehicles online in Texas, that this isn't a big deal.
The sales tax is paid in the state where you accept delivery. If you accept delivery in your home state, the sales tax will be paid to that state.
If you wanted to pick up your car in California, then things get much more complicated. You have to pay the CA taxes to pick up the car, and then will likely have to pay taxes again when you register the car in your home state. We looked into that for our X purchase last summer - and decided that was a really bad idea...
The local Service Center will handle all of the delivery issues. The only big change is that you may not be able to pay them for your vehicle, and will be required to make your payment through the Tesla website or your mobile app - and not give a check to the Service Center. Otherwise, they should be able to handle everything else, including inspections, ordering license plates, sales tax, ...
Tesla will have to work out the test drive issue - because some customers will want to do a test drive before ordering or before delivery.
The process for returning a vehicle will also be challenging for Tesla. They require customers to pay for a vehicle before taking ownership. The same will be true when returning a car back to Tesla - the owner will expect to walk away with their $$ once Tesla has the vehicle, so they'll be able to go across the street and buy a vehicle from another source.
This is the direction the auto industry is going. New companies are shifting to used car sales online (like Carvana). Even our local dealerships are beginning to sell their new & used vehicles online.
The stores were a short term solution - especially useful when there were few Tesla vehicles on the road. From a business standpoint, it makes sense for Tesla to avoid the additional costs of the stores - and will put even more pressure on the other manufacturers to produce EVs competing with Tesla on price, performance, range and features.