Update CHANGES.md after 2.64 release cut (#34793)

Author: Abacn

CHANGES.md

@@ -58,7 +58,11 @@
 * ([#X](https://github.com/apache/beam/issues/X)).
 -->
 
-# [2.65.0] - Unreleased
+# [2.66.0] - Unreleased
+
+## Beam 3.0.0 Development Highlights
+
+* New highly anticipated feature ([X](https://github.com/apache/beam/issues/X)) to address Milestone Y ([#Y](https://github.com/apache/beam/issues/Y)).
 
 ## Highlights
 
@@ -68,8 +72,6 @@
 ## I/Os
 
 * Support for X source added (Java/Python) ([#X](https://github.com/apache/beam/issues/X)).
-* Upgraded GoogleAdsAPI to v19 for GoogleAdsIO (Java) ([#34497](https://github.com/apache/beam/pull/34497)). Changed PTransform method from version-specified (`v17()`) to `current()` for better backward compatibility in the future.
-* Added support for writing to Pubsub with ordering keys (Java) ([#21162](https://github.com/apache/beam/issues/21162))
 
 ## New Features / Improvements
 
@@ -78,6 +80,36 @@
 ## Breaking Changes
 
 * X behavior was changed ([#X](https://github.com/apache/beam/issues/X)).
+
+## Deprecations
+
+* X behavior is deprecated and will be removed in X versions ([#X](https://github.com/apache/beam/issues/X)).
+
+## Bugfixes
+
+* Fixed X (Java/Python) ([#X](https://github.com/apache/beam/issues/X)).
+
+## Security Fixes
+* Fixed [CVE-YYYY-NNNN](https://www.cve.org/CVERecord?id=CVE-YYYY-NNNN) (Java/Python/Go) ([#X](https://github.com/apache/beam/issues/X)).
+
+## Known Issues
+
+[comment]: # ( When updating known issues after release, make sure also update website blog in website/www/site/content/blog.)
+* ([#X](https://github.com/apache/beam/issues/X)).
+
+# [2.65.0] - Unreleased
+
+## I/Os
+
+* Upgraded GoogleAdsAPI to v19 for GoogleAdsIO (Java) ([#34497](https://github.com/apache/beam/pull/34497)). Changed PTransform method from version-specified (`v17()`) to `current()` for better backward compatibility in the future.
+* Added support for writing to Pubsub with ordering keys (Java) ([#21162](https://github.com/apache/beam/issues/21162))
+
+## New Features / Improvements
+
+* Added support for streaming side-inputs in the Spark Classic runner ([#18136](https://github.com/apache/beam/issues/18136)).
+
+## Breaking Changes
+
 * [Python] Reshuffle now preserves PaneInfo, where previously PaneInfo was lost
   after reshuffle. To opt out of this change, set the
   update_compatibility_version to a previous Beam version e.g. "2.64.0".
@@ -93,26 +125,22 @@
 
 ## Deprecations
 
-* X behavior is deprecated and will be removed in X versions ([#X](https://github.com/apache/beam/issues/X)).
-* Added support for streaming side-inputs in the Spark Classic runner ([#18136](https://github.com/apache/beam/issues/18136)).
 * Beam ZetaSQL is deprecated and will be removed no earlier than Beam 2.68.0 ([#34423](https://github.com/apache/beam/issues/34423)).
   Users are recommended to switch to [Calcite SQL](https://beam.apache.org/documentation/dsls/sql/calcite/overview/) dialect.
 
 ## Bugfixes
 
-* Fixed X (Java/Python) ([#X](https://github.com/apache/beam/issues/X)).
 * Fixed read Beam rows from cross-lang transform (for example, ReadFromJdbc) involving negative 32-bit integers incorrectly decoded to large integers ([#34089](https://github.com/apache/beam/issues/34089))
 * (Java) Fixed SDF-based KafkaIO (ReadFromKafkaViaSDF) to properly handle custom deserializers that extend Deserializer<Row> interface([#34505](https://github.com/apache/beam/pull/34505))
 * [Python] `TypedDict` typehints are now compatible with `Mapping` and `Dict` type annotations.
 
 ## Security Fixes
-* Fixed [CVE-YYYY-NNNN](https://www.cve.org/CVERecord?id=CVE-YYYY-NNNN) (Java/Python/Go) ([#X](https://github.com/apache/beam/issues/X)).
+
 * Fixed [CVE-2025-30065](https://www.cve.org/CVERecord?id=CVE-2025-30065) (Java) ([#34573](https://github.com/apache/beam/pull/34573))
 
 ## Known Issues
 
-[comment]: # ( When updating known issues after release, make sure also update website blog in website/www/site/content/blog.)
-* ([#X](https://github.com/apache/beam/issues/X)).
+N/A
 
 # [2.64.0] - 2025-03-31