Buying a Threadripper with an AiO liquid cooler might be the only way to cool it down as these 16-core and 12-core beasts will probably have 180W TDP. The second reason is that it will be quite hard to find a cooler that will support the upcoming TR4 socket as we doubt that many cooler manufacturers will offer such coolers from day one, especially since this is a market for enthusiasts.
We still haven't heard anything regarding coolers that support TR4 socket and bear in mind that this is a big socket and cooler manufacturers can't simply add an adapter bracket but have to make a completely new design.
The report coming from Hermitage Akihabara states that AMD Ryzen Threadripper will be available on August 10th in Japan and should be bundled with an AiO cooler. There is no information on which AiO cooler will AMD use, but Asetek or Cooler Master are the best guesses.
AMD already officially announced that first TR4 socket motherboard, based on AMD's new X399 chipset, as well as two Threadripper SKUs, the Threadripper 1950X and the Threadripper 1920X, will be available in early August with the price set at US $999 and US $799, respectively.