According to various transcripts/reports of today's announcements (including The Pom Queen's above), existing 457 holders are to be exempt of these new rules as part of the agreement.
I am currently in this situation. Under 45, 6 years experience in field, and a good chunk above the minimum salary threshold.
My ANZSCO code now appears on the short term list, which if i understand correctly actually means i'm still eligible for a Direct Entry 186 PR visa (according to the supporting border website material online). However, i wait with baited breath to see if any further definition of this 'grandfathering agreement' emerges.
I'm only 5 weeks away from my 2 year anniversary on my 457, and just on the cusp of finishing gathering documents for a TRT stream 186 application. For now though, after much research this evening, i'll just about sleep tonight.
Fingers crossed for everyone!