With the caveat that we know everything is still in flux and under discussion...
Right now the game is in a real lame duck mode. Itemization is about to be completely overhauled and there's little incentive right now to keep at the item chase, particularly when getting uniques is a major part of that chase. Uniques are scheduled to become obsolete and stop dropping, though old uniques will continue to exist as legacy (but furtherly unobtainable) items.
This is about the worst situation possible right now.
You're left wondering if you should be hoarding Uniques (because they wont be obtainable anymore) or start to clear them out of your STASH (because you'll replace them all with Omega items anyway). You're left wondering if there's any point to upgrading the ones you have now or trying to acquire more good ones, because there's no indication that high-rolled uniques will have any value in the new system. The assumption is that Omega items will always be better, but there's also the possibility that legacy Uniques remain BIS for some builds, too, and then you definitely want to still have a couple on hand if they're not dropping anymore.
I'd like a little clarification, at least in a broad general sense, if there'll be any conversion of value for uniques right now. We know the intention is that StarkCubes will be turned into Ancient Devices, at least. Will Uniques be convertible to their corresponding Omega items? Will they be convertible to something else of value? Will high-rolled uniques have any greater value than trash-rolled ones, ie a well-rolled Unique will convert to a well-rolled or higher-level Omega version of itself?
Or is the design intent just that you use whatever Uniques you still have equipped until you get an Omega to replace them with, then just vendor them? Should we just go ahead and clear all the rare and powerful Uniques we're saving in our STASH right now?
It'd just be nice to know what we're getting right now that we'll still be able to "take with us" next month.