Next year? I thought the rumors where this year?
Rumors keep tightly coupling this SE 4 with the Apple modem. The Apple modem keeps sliding into the future ( 'next year', then 'next year ' again. rinse and repeat.)
Somewhat similar to Apple haggling for $20 screens when the vendor producing them now ( with all the R&D markdown of just selling an 'old' product they already make ) is at $30 ( Apple looking to shave another 33% off the cost). Same thing with the modem costs... probably trying to drive the costs down by a hefty margin.
Decent chance that the first production Apple modem doesn't have 5G mmWave ( only sub6). The SE is the only iPhone line left that can 'accept' that limitation. ( Qualcomm is still going to get the contract for the upper range iPhones as Apple can't 'cover' those Qualcomm x79 (and up ) abilities for several more years.

Apple Extends Modem Licensing Deal With Qualcomm Through March 2027
Apple has extended its modem chip licensing agreement with Qualcomm through March 2027, Qualcomm said today during its first earnings call of 2024....

)
When there was a large hype train about how Apple would kill the Qualcomm modems in a couple of years, the SE 4 was on a faster track.
Same line of constraints , is the swapping the extremely mature TouchID for FaceID ( and dynamic island). It is just cheaper to wait another year for those subcomponents to get closer to being as inexpensive as Touch ID is.
( likely not going to be a price-to-price even trade-off which is likley pushing these Scrooge McDuck tactics on the screen and modem bill of material costs. )
SE --> SE2 was 4 years ( 2016 - 2020 ). SE2 --> SE3 was 2 years ... but much more minor change ( SoC and Radio swap out). 2022 + 3 years is about 2025. It wouldn't be too surprising if there were modem hiccups to slide into 2026 ( same 4 year gap that last major form factor change had).