Will ranked and unranked Greater Rift Keystones convert to new Greater Rift Keystones in v2.3?

From the current 2.3.0 PTR Patch Notes:

About Nephalem Rifts and Keystones

• Nephalem Rifts no longer require Keystones

About Greater Rifts and Greater Rift Keystones

• Generic Greater Rift Keystones now drop and can drop at any difficulty level
• The Realm of Trials has been removed from the game
• Greater Rift tiers are now selected via a dropdown menu
• Greater Rift tiers are now selected via a dropdown menu (The maximum rift tier that can be selected is: Your previous best, or one tier higher than the highest Greater Rift you have successfully completed)

So to answer your question:

• Your Rift Keystone Fragments will become garbage (as you'll no longer need them to enter a Nephalem Rift)
• Your Greater Rift Keystones, both ranked and trial keystones, will become the new unranked Greater Rift Keystones and you'll be able to select the level of your choice thanks to a dropdown menu

The advised course of action to prepare for 2.3:

• Use all your Rift Keystone Fragments to generate as many GR Keystones as you can to farm the new patch sets, etc, once the patch is live, plus you won't be bothered with the trials anymore
• Transform your current GR Keystones into too high leveled GR Keystones that you can't actually do (if your gems are too leveled up to consider that option) as they will be changed into generic GR Keystone that you will be able to farm again in 2.3

Disclaimer: The PTR is of course subject to chance but I highly doubt these will be subject to change, as the feedback concerning the keystones has only been positive on the PTR.