Patch 4.3 is in the works with a projected release sometime in November. New things for 4.3 include the Transmogrifier, Raid Finder, Void Storage, the final Cataclysm raid featuring Deathwing, 3 new 5 mans and more. There's plenty of coverage elsewhere (MMO Champion for one) on all the new stuff Blizzard has told us about. I'm going to speculate on something they still haven't told us about, Epic Gems.
Since this is the final content patch for Cataclysm, if they're going to introduce new Epic Gems it pretty much has to be in 4.3. The problem is predicting whether or not they *will introduce them at all and if they do how they'll be obtained.
I'm torn as to whether or not they will.
On the one hand if they don't give us epic gems in this expansion there will be a lot of complaints and Blizzard has to know that. When enough players complain loudly enough for long enough and demand something Blizzard usually gives them what they want.
On the other hand in spite of constant questions regarding Epic Gems ever since Cataclysm was released Blizzard still hasn't said a thing about them. It might be they don't intend to add them but don't want to tell us so either because they know how the player base would react.
IMO Blizzard seems intent on nerfing JewelCrafting profits in Cataclysm with things like a virtually endless supply of cheap uncommon gems, no cooldown on rare gem transmutes and a complete lack of epic crafted rings and necks. Assuming I'm right about that then they'll either not add epic gems or if they do they'll make them easy to obtain to keep the supply up and prices down... Or they could even make them extremely difficult and expensive to obtain though I doubt they'll go that way.
If they do introduce epic gems then there's a whole bunch of questions regarding the difficulty of obtaining them and the ways in which we'll be able to obtain them.
How easy or difficult will it be to obtain them? Will we be flooded with cheap epic gems like we are with rare gems now or will they be costly and in short supply?
How many different ways will there be to obtain them? Mining, prospecting, transmutes, vendors, boss drops, something new?
If we can prospect them, will they come from Pyrite, Obsidium, Elementium or some entirely new ore?
If there is a new ore, will it be found in the world or new 5 mans or only in the new raid?
If there are transmutes what will the mats be?
Will there be a cooldown on the transmutes?
Will we be able to purchase them with honor, justice or valor points?
If so will it take a lot of points or just a few?
What about a vendor selling epic gems for gold, lesser gems or something else?
If they drop from bosses will they drop from raid bosses, 5 man bosses or both?
Only bosses in new instances or existing instances too?
Some entirely new method of obtaining them?
If they're easy to obtain then prices might start out high but we'll be in an oversupply situation and eventually the campers will drive prices into the ground just like rare gems.
On my server a lot seem to be stockpiling pyrite ore lately and prices have skyrocketed. If we don't get epic gems from pyrite in 4.3 I figure most of the pyrite stockpilers will start dumping it and prices will plummet.
In conclusion, nobody knows for sure what's going to happen. It's up to you to make the risk assessment for yourself and decide what to do about it. Personally I'm taking a pessimistic view, either there won't be any epic gems at all or there will be something we won't like about how they're obtained. Pyrite prices are too high on Antonidas to stockpile right now. I still buy it when I find some cheap enough but that all goes into making Ebonsteel Belt Buckles. I am keeping a nice stockpile of everything I can think of (rare and uncommon gems, herbs, volatiles, etc.) that might be used for transmutes just in case we get epic gems and a no cooldown transmute to make them with.