Are you referring to Tesla's 4680's or the cells that Tesla gets from Pansonic?
Re: Panasonic
Tesla's been refining their cells with Panasonic for quite awhile and have done things like substantially reduced the cobalt used compared to others (at least as of couple years ago). I'm not sure what the differences in wh/kg are compared to others today.
Panasonic is also much more efficient at making those cells at scale which gives Tesla an edge on their cost.
Tesla has always made their own batteries (the grouping of the cells). Their battery + BMS on the other hand is substantially better than other manufacturers. They can manufacture the battery much cheaper than others, and the BMS keeps it running smoothly.
For example - The Fords Mach E performance model can't (or couldn't) even do more than a launch or two before having to throttle itself due to heat. They currently have recalls happening due to contactors having problems with heat.
Re: Tesla's 4680 Cells
Right now, they're nothing special from a wh/kg perspective, what they're main goal for them is to be substantially cheaper to manufacture than the cells other manufactures make. If you can make them for 2/3 the cost you'll have huge advantage over everyone else, and then also you don't have to pay the mark up to Panasonic or LG either.
Only time will tell if their chemistry/anode/cathode improvements will make their cells better than what other manufactures are producing now and in the future. Personally, I'd be nervous to get a 1st / 2nd gen version of these cells/batteries while they work things out.
Re: Solid state
If that ever happens and they are cost competitive to produce, then that'll be a big deal ya. What if they aren't cost competitive though?
Will you be willing to pay $10-15k more for the same range but faster charging, higher safety, and more lifecycles?
You're right though, they are the future eventually.