Thanks for the clarification as well, Jeff.
The information I provided above only applies to apps deployed using the Java 8 runtime on GAE Standard, though. I’m currently not aware of circumstances when a F1 instance would allocate 256 MB when in use with Python 2.7 on GAE Standard.
In any case, replying to your initial question, there currently aren't any changes to the size and speed of instance classes on GAE Standard. Apart from the small aside on the Java runtime I explained above, the official documentation [1] indeed provides accurate info regarding how much heap memory and CPU your application has available for usage.