This is all my opinion, but I feel like the "event" will be almost exclusively set to sell the Plaid. At announcement, the Plaid really didn't offer much in a way to differentiate itself from the LR. Most of the news we've received applied to Paladium updates, which apply to both cars. The Plaid had the third motor and faster 0-60 times, but that was knocked a bit by reports of the rolling start and it also had a lower range when compared to the LR. I realize the range difference isn't much, but because one is over 400 and one under, psychologically, that can be impactful. There's a reason companies list prices as $3.99 and not $4.00.
With the Plaid+ listed on the site, they never really took the time to "Establish" the awesomeness of the Plaid. There was a Plaid+ coming on the order page that would be faster and goes so much farther with likely newer battery technology. I'd wager that their Plaid sales were much lower than they wanted. So they remove the Plaid+ (since it's so far out and really only confusing potential Plaid buyers) and try and convert as many of those as possible to Plaid. Then I think they are looking to try and add a few specific features to the Plaid to make it more attractive (like carbon fiber spoiler, and matching door handles, I would bet there are a few more Plaid "surprises" announced here to generate buzz). I doubt anything that will be radically different, but enough to help get all the news outlets to publish articles about some new Plaid exclusive features (which may or may not be for LR as well).
I think they know the LR will sell itself. It's super fast and has crazy range already, they don't need to build any demand there. But the king is the Plaid, and they shot themselves in the foot by the confusion of if/when the Plaid+ is coming and the features that are shared with the LR.
This is obviously just a guess, but for the next 7 days, what else are we going to do?
