Taken from todays Codan (Minelab) stock exchange report for financial year ending 30th june 2020. Im assuming they are referring to the GPX6000.
"DuringFY21, Minelab will introduce a new gold detector, which will include the best features from both the SDC 2300®and GPX platforms"
So FY21 ends 30th June 2021 therefore we can expect product launch before 30th June. My guess is March 2021 - just before everyone heads over to Western Australian gold fields for the cooler months.
Best Feature of SDC - very robust, deadly on small gold, compact, water proof.
Best Feature of GPX - very stable in high mineral soils, can easily swap with wide range of coils to suit conditions, easy to swing.
Add blue tooth headphones (and maybe some new Geo Sense -PI (what ever that is)) and presto you have the GPX 6000.