Sounds like this has stalled out for a little while.
I can't imagine there will be any conversion until an entire academy class has been issued Gen 4 17s, and that is many months away. Supposedly there were going to be a few selected for 9mm T&E, but that hasn't happened yet as far as I know.
I think the technology arguments are bullshit. It isn't like 9mm advances in a bubble. Any improvements in .355 projectiles are also concurrently made in .40 projectiles. If we can get 22 mag to penetrate to 18", are we going to declare that due to "higher capacity" and "less recoil" and "the overriding importance of shot placement" that 9mm and higher are obsolete?
I don't mind 9mm. I've got quite a bit of time carrying one around in DOD. But knowing that the first shot matters, the first shot for any caliber IS THE EXACT SAME, I don't mind .40 as a duty round. If anything the result of all this should be the choice among LE professionals to choose the caliber that is right for them, be it 9mm, 40, 45 or (if you like spending $1+ a round, .357 sig).