The question is will the RWD version be capable of much more than 250kW? The tri-motor design will easily be capable of 500kW since it is going to use two packs that are stacked. (According to MotorTrend.)
But where will it get that? Supercharger V4? Megacharger stalls used for the Tesla Semi? (Makes sense especially if you are towing in the Cybertruck.)
A double-thickness pack is not "two packs that are stacked". That would entirely double the pack mass. A double-thickness pack has two cells, one on top of the other - or alternatively, a larger format (taller) cell, and saves significant mass over two physical stacked packs.
As for why S/X is very unlikely to have double the capacity (let alone range).
1) S/X is not designed for that volume of cells. It'll be hard enough to fit in
any more capacity, let alone double.
2) It's not designed for that weight. The last thing they want to have to do is reengineer the structure.
3) It'd reduce the number of cars Tesla can make by consuming twice as many cells
4) The incremental amount of sales increase would not justify #3. S/X already dominate the range market dramatically vs. the "competition".
5) As already mentioned, higher-end vehicles need to have higher stats to justify their higher prices. What's the point of the Roadster if you're basically giving S Plaid the Roadster's stats? Why would people pay $250k for it when they can get the same thing but with a lot more room for half the price?
6) Is S Plaid supposed to just stagnate for the next several years? No? So it's going to be even
more range than the Roadster for half the price?
7) It's totally out of line with the historic rate of range improvement in Teslas.
It's pure wishful thinking. Just like the endless droning for the past three years about the "imminent 2170 S/X release". I had to spend years in this endless game of whack-a-mole against the wishful thinking crowd insisting that nobody should buy an S/X because it'd soon be obsolete due to some 2170 S/X superpack. Years of needless suppression of S/X sales. Is this going to be the new wishful thinking game now?
Yes, Plaid is now
finally getting a new pack next summer.
No, it's not going to have 500 miles range and charge at 500kW. Sorry. That car will only exist in your dreams, at least for the next several years.
Plaid is a track-optimized version of S/X. That's all it's ever been presented as. It has A) a new 3-motor powertrain and B) a pack architecture designed for better cooling, along with C) fascia/radiator changes for better cooling, D) fascia changes for the wider tires, and E) some sort of spoiler / wing system in the rear (which I expect to most likely be retractable, otherwise it'll ruin the highway energy consumption).
Everything else is just people pushing their wishes into it.