I saw this as well, really hope this
"Existing 457 visa holders and applicants as at 18 April 2017 will continue to have access to existing employer sponsored pathways to permanent residence. Further details will be published on the Department's website in due course."
is the whole truth, not just the grace period...
But anyway, those whose TRT point is after Mach 2018 (like myself) should probably start to make a plan B....