Yes, there will be one-off authorisation required before an app can send events to another app. There will be some exceptions — including unsigned applets —but it will probably be more annoyance to end-users than scripters.

There’ll also be restrictions on accessing some protected data (emails, picture library, contacts, etc) which will be more problematic to work around.

The article you refer to makes some good points, although I suspect most of them won’t matter too much to most scripters. However his request to be able to whitelist apps, and do it in advance, would certainly be useful in some case. I think it would be useful for scripters to duplicate his bug with Apple, to hopefully give it a bit more weight.

Longer term, the move to compulsory notiarization of codesigned apps will probably require a bit more thought.