Looks like they continue as independent company, owned by Softbank,
https://blog.treasuredata.com/blog/2020/09/14/nvidia-to-acqu...> The transaction does not include Arm’s IoT Services Group, which is made up of Treasure Data and Arm’s IoT Platform business.
> Back in July, Arm announced a proposed transfer to separate Treasure Data from its core semiconductor IP licensing business, enabling Treasure Data to operate as an independent business. That separation is on track and will be completed before the close of the NVIDIA transaction. Most importantly, you should not see any disruption in our service or support as a result of this news.