I don't believe that to be the case, so I contacted Rivian yesterday. I was told definitively that the Amazon vehicles are on a separate production and delivery track which will not supplant the R1T/S production schedule. The Amazon contract has specific deliverables which Rivian is on schedule to meet. Rivian is currently adding an additional 1500 employees to ramp up the production/delivery of the vans and T/S. Bezos is a huge investor in Rivian and is banking on their success; in producing his vans as well as the R1T/S. I think we all need to just be patient!
I wrote most of this another post, but it's also relevant here. The Amazon contract represents the opportunity for a somewhat firm100k vehicles. Rivian is (excuse the pun), in the driver's seat with respect to Amazon. They are the first company that will supply Amazon with EVs, and have it within their power not only to have a very solid, 10 year revenue stream from that, but to also cement themselves as the delivery truck supplier of choice. All they need to do (he said somewhat sarcastically) is to to deliver a quality vehicle on time and on budget. No other EV maker is presently in this position.
As the economists say, we live in a world of scarce resources. While it may be possible for Rivian to do things simultaneously (i. e., produce & delver both the delivery truck and the R1T/S - and in the case of the R1S Max, finish the design), I think it's unlikely that a start-up can do all of that. When push comes to shove, as I believe it surely will, and likely sooner rather than later, I think that Rivian will concentrate their not unlimited resources on the Amazon contract.
Rivian needs to deliver 10,000 Amazon trucks in 2022, which means that they need to move from low-rate initial production (the current state) to full production in a short time. With the revenue from 100,000 sales - at a minimum - on the line, for Rivian to focus on Amazon seems more than reasonable, in my view. That there is a separate production line is good, but may not really be all that relevant. If (perhaps more likely given the newness of both the company and the products, when) there is an issue with the Amazon line that negatively impacts production and/or deliveries, the response is almost certainly going to be throwing resources, including personnel, at the problem.
This doesn't mean that Rivian will completely neglect the consumer vehicle side of the house. But what it does mean (possibly? probably?) is that the R1T and S ramp up will be be slowed. That may cause some of the 48,000 pre-order holders to jump ship, but there are really no direct competitors, at least not at the moment. I don't think that many R1T buyers are likely to migrate to the Tesla CT or even the F-150 Lightning; and I think it's even less likely for R1S buyers to jump to the GM Hummer. If I'm right about a slower ramp-up to R1T/S production (what I believe will be the case to some extent, even absent issues on the Amazon contract), Rivian won't really suffer much from lost sales, or even in branding, assuming they deliver at least a few thousand pick-ups and SUVs in 2022.
My conclusion is that Rivian has more at stake with the Amazon contract and will likely prioritize it at the expense of production of the R1T & S, for the reasons outlined above.This is merely opinion however, and rooted in 30 years of experience in aerospace manufacturing that may or may not be relevant to the automotive world. As someone who put a pre-order in only 18 months ago, I don't really expect the R1S Max that I want to be in my driveway before the end of 2023 and perhaps not until 2024. I'm betting that it will be worth the wait however.