A designate target feature, even combined with the present top attack missiles, would be really interesting and, if the developers decide to not give to him a direct fire agtm, would any way rebalance it. Designating a suitable target, one that is actually damaged by his missiles, and then targeting him with the right mouse button you could fire 4 or 6 top down agtms on him, does not matter if he uses the smoke, retreats behind cover or even if you retreat under cover or run away as he is chasing you.
At now it is possible to do something similar but only if a craptank and let's say a sphinx are used in tandem by a platoon of 2, better coordinating in vocal chat, the spinx can designate and fire 2 missiles, then try to track with the AC, but even failing at it other 4 or 6 hits, depending on the duration of the designation, are assured by the K153-C.
EDIT: with the sphinx 20 sec designation the K153-C should be able to fire 4 missiles, both with the breach retro and without it, before it expires, for let's say 2K damage, maybe a little more, that added to the one of the spinx 2 agtms is enough to kill even some low HP mbt and more then enough to bring the others to a very low health and kill almost every other tank, but if instead of a sphinx the craptank works behind a K2 then the things become even more interesting as the designation last a lot more so 6 or maybe even 8 hits are assured.
Surely if the tank can designate himself it is even better as has more freedom to move on the battlefield and punish every single tank that remains visible long enough to be designated. I suppose that with the designation feature this tank would become quickly hated by most of the other tank drivers as being designated in a not Anders, not Termi, not PL and not few MBTs is equal to receive 2K damage with no save possible.