According to some entries in German zoo forums, the EAZA plans to start breeding a number of gazella including Gerenuks! So there definitely should be more animals in Europe soon. Of course they will have to take the capacities from somewhere, though...
By the way: The last remaining fishing cat left the Tierpark to Nuremberg. Also, the Elephant Shrew left to Pilsen. And the last two wolves died recently. So there probably will be more changes soon. The vacant enclosures will come in handy, as the boxes in- and outside the Brehm building will be remodelled for some 5 mio € rather soon. Even the sun bears will finally receive a new enclosure then. Most bad/ unattractive enclosures will be history soon. The boxes in and outside the monkey building also have been and continue to be remodelled. Some of the large green fences have been covered with small stems and some of the lower ones (the ones to keep visitors away) have been removed or replaced as well.
Other than that, Knieriem just unveiled a new free-of-charge visitor's train which complements the old one (4€/ 2€). It looks very attractive and is equipped with heating and AC. But it only goes a comparatively small round, missing all major buildings as well as the mountain area. Still it definitely is an additional attraction/ service. The same goes for the new signposts and area maps that have been introduced. Or the extension of the pre-existing playing ground and the construction of a new playing one as well as the remodelling of the large old open air show arena which will all start soon.
Oh, and the sand can indeed be used for landscape construction (hill areas). Newest results show that the contamination is nowhere as dramatic as earlier reports speculated. Of course, this will still mean additional investments, but it may also still improve the beautiful array of different landscapes (old forest, mountain zoo, open paddocks, castle grounds) found in the park. I am hopeful for the future. It mainly depends on the funding now. And of course everybody waits for the new plan to be released soon (it apparantly comprises some 180 pages and is virtually finished, though it still goes through some Revision/ modification)...