The upcoming tablets will obviously keep the AMOLED technology of their predecessors' displays. The new models will be SM-T710 and SM-T810 (the originals are SM-T700 and SM-T800, respectively).
While no other details about the new devices are known at this time, it's safe to assume that they won't get some earth-shattering hardware upgrades. We might see them ship with a new chipset, perhaps Samsung's Exynos 7420 which is expected to make its debut in the Galaxy S6 on March 1.
That may help the new Tab S generation perform better than the original tablets. We apparently shouldn't expect to see the new Tab S line unveiled at MWC alongside the Galaxy S6, since work on them isn't that advanced yet. They will be announced later, perhaps towards the middle of the year.