According to the latest info shared by @yuuki_ans on Twitter, the Core i3 chips from Intel’s 12th Gen Alder lake-S stack will retain an older architecture, most likely in the form of the 14nm Cypress Cove core featured in the 11th Gen parts. It’s worth noting that in a similar manner the current-gen (RKL-S) Core i3s are based on older architecture, essentially a Skylake refresh from the 10th Gen Comet Lake stack.
The source claims that while the Core i3 has undergone some changes (most likely with respect to the GPU), it is based on the same architecture as the 11th Gen lineup. This most likely refers to the 11th Gen Rocket Lake-S processors which are based on the 14nm backport of Sunny Cove (Cypress Cove), it could also mean the 10nm-class Willow Cove cores featured in Tiger Lake.
As for the reasons why Intel might go with this strategy, the answer is rather clear. AMD’s performance in the lower-end market over the last several years has been quite poor. The Ryzen 3 3300X launched much later than its Zen 2 brethren and has been out of stock for most of this and last year. Courtesy of the chip shortages, we’re yet to see a successor to the Ryzen 5 3600 and 3700X, with the lowest-end Zen 3 SKU starting at $329 in the form of the 5600X.
If you look at the Alder Lake specs derived from the Linux Coreboot code, there are several SKUs with only performance cores and no efficiency cores. These could be the refreshes based on Cypress or Willow Cove that have been retained to increase profit margins and/or reduce the strain on Intel’s 10nm capacity. At this point, it’s hard to say anything with 100% certainly, so be sure to take this report with a grain of salt.