I think apple will keep the current 27" Thunderbolt Display, but also make a 30" or 32" 4K display. Who knows if it will be matte or glossy (hoping for matte) but hopefully it will be 16:10 and not 16:9.
The 4K seem doubtful for right now. In a couple of years sure. Right now no.
First, 4K displays are likely to be highly dynamic over the next 1-2 years. They are are $4K now but next year there will be alternatives at lower than that. Year after that lower still. Contrast this will Apple who likes to slap a price on something and just stick with the same single price for years.
Second, it doubtful anyone is going to give Apple "two year into the future" discounts on 4K panels no to erode even faster the potention to get the R&D back they have put into the panels. Perhaps Sharp was desperate, but for Apple is it dubious to push company killing discounts on your supplier. Long term that keeps Samsung in the drivers seat if kill off their competitors for them.
Third , if the 3rd party vendors have displayPort and/or HDMI 4K inputs then they'll just work just fine. Apple doesn't have to sell every display. They currently make no high gamut ones. Why would have make highly specialized 4K video monitors with volatile pricing?
What Apple really more desperately needs is a 21.5" Thunderbolt display at around $499-599. Same derived iMac infrastructure, but at a lower price point. Having two monitor set-ups is far more common among Mac Pros.
2 * $599 ==> ~$1,299 ( or better still 2 * $499 ==> ~$1,000)
goes down alot easier than
2 * $999 ==> ~2,000 ( probably roughly in same ballpark as entry level Mac Pro itself).
Also what Apple needs is to get more honest with product naming (along with obviously the newer iMac bonded lcd panel solution) with the current product transitioned to:
Apple Thunderbolt Docking Station ( with MagSafe connector aimed at laptops )
and add 21.5" and 27" models of :
Apple Thunderbolt Display ( with NO MagSafe connector and a removable TB cord so can use longer ones. ) Throw in two rather than one FW ports and upgrade to USB 3.0 on these models.
So in two monitor set up with 2013 Mac Pro deployed system would have:
10 USB 3.0 ports.
4 FW ports ( and two independent FW controllers )
4 1GbE ports
with no "extra" power cords. That is actually better than current Mac Pro ( 5 USB 2.0 , 4 FW , 2 1GbE )