
The specific models of Apple Watches that will no longer support the upcoming watchOS 11 are:
These models will not receive the watchOS 11 update and will stick with the current watchOS 10 software. However, they will still continue to function, and if there are security issues, Apple can still patch those with new watchOS 10 security updates.

The Apple Watch Series 4, Series 5, and the first-generation Apple Watch SE were specifically chosen to lose support for the new watchOS 11 due to their older chipsets and processing power. All three models are powered by the S4 or S5 chips, which were first released in September 2018 with the Apple Watch Series 4.
The new watchOS 11 comes with advanced features and improvements that demand higher processing capabilities. The older chips in these models may not be able to handle the processing demands of the new OS, leading to potential performance issues. As a result, Apple decided not to support these models with the new watchOS 11 update.
However, it's important to note that these models will continue to function with the current watchOS 10 software, and Apple can still provide security updates if needed.

watchOS 11, announced at WWDC 2024, brings several new features and improvements to compatible Apple Watch models. Here's a summary of the main updates:
Vitals App: This new app provides a snapshot of key health metrics, including heart rate, respiratory rate, wrist temperature, sleep duration, and blood oxygen levels. It offers insights into daily health and notifies users when two or more metrics are out of their typical range.
Training Load: This feature measures the impact of workouts on the user's body over time. It offers insights into the strain on the body from workouts over the last seven days compared to the last 28 days, helping users make informed decisions about their training.
Customization for Activity Rings and Fitness App: Users can now pause their Activity Rings for rest days or customize their goals based on the day of the week. The Fitness app on linked iPhones allows users to customize the Summary tab to display specific information they want.
Smarter Smart Stack: The Smart Stack interface has been made more intelligent, suggesting widgets based on time, date, location, and daily routines. It offers new widgets, including Shazam, Photos, Distance, and more.
Personalization for Photos Watch Face: Using machine learning, watchOS 11 can analyze photos and recommend the best ones to use as watch faces based on aesthetics, composition, and facial expressions.
Improved Pregnancy Tracking: The Cycle Tracking app now detects when users log a pregnancy in the Health app on iPhone or iPad, allowing them to track their gestational age and log pregnancy-related symptoms.
Check-in Functionality: The Check-in feature is now available on Apple Watch, integrated into the Workout app for people going on late-night runs or walks in potentially unsafe areas.
Translation App: The Translate iPhone app is now available on watchOS 11, allowing users to access translations for 20 supported languages directly on their wrist.
Tap to Cash: Users can now send and receive Apple Cash by simply holding their Apple Watch near another Apple Watch or iPhone.
Enhanced Ticketing: Improved ticketing provides users with more information on tickets in Apple Wallet, such as when the venue opens and when the show starts.
Please note that watchOS 11 will be compatible with Apple Watch Series 6 and newer models, dropping support for Series 4, Series 5, and the first-generation Apple Watch SE.