They released an ISO for Update 1, so chances are there will be one for Update 2.

In the meantime, you can download the online installer [1] and run

    vs2015.2.exe /Layout

to launch the downloader, which should create a folder which contains everything that you would find on the update ISO. (EDIT: This seems to result in a 4.53 GiB download, so definitely smaller than the 6.95 GiB full install ISO.)

[1]: http://go.microsoft.com/fwlink/?LinkId=691129