The person you are replying to did not explicitly identify 'we' as referring to the USA. Fossil fuel pollution and climate change is a global problem; the atmosphere knows no national borders. Globally we are still dependent on Saudi Arabia for oil and Tesla is having a global impact in lessening that dependency
Fracking shale oil is a bad investment. Most of the drilling and exploration companies heavily involved in shale oil "tight oil" fracking are suffering financially due to poor estimates of well productivity and longevity. The primary reason for low oil prices in the Permian is due to a lack of pipeline in that region. The US is not actually self-sufficient in regards to crude oil used to refine into gasoline and other fuel products.
Oil is fungible. We're on oil as long as Saudi Arabia is contributing oil to the global marketplace. Take their oil off the marketplace, watch the price skyrocket.
Not really; the issue with Saudi oil has mostly not been direct imports US has (both as a net importer and net exporter) for some time gotten more of it's gross imports from other, nearer sources.
The issue for the US with Saudi oil has been global oil prices and the knock-on effects on, well, everything else.