The very nice things about Class C is that no uplinks are required to trigger a possible downlink, and that multicast is supported. So: less waste of air time and backend computing power. But still then, downlinks are always expensive for gateways, and without an uplink to trigger it, TTN would not even know which gateway is the best to use for the downlink?
So I’d guess that for Class C one cannot expect the number of downlinks to be (much) greater than the maximum of 10 per day as currently defined by TTN?