Hi,
so, Tor has included a feature to fetch the initial consensus from nodes other than the authorities for a while now. We just haven't shipped a list of alternate locations for clients to go to yet.
Reasons why we might want to ship tor with a list of additional places where clients can find the consensus is that it makes authority reachability and BW less important.
At the last Tor dev meeting we came up with a list of arbitrary requirements that nodes should meet to be included in this list.
We want them to have been around and using their current key, address, and port for a while now (120 days), and have been running, a guard, and a v2 directory mirror for most of that time.
I have written a script to come up with a list of notes that match our criteria. It's currently at https://www.palfrader.org/volatile/fallback-dir/get-fallback-dir-candidates
It currently produces https://www.palfrader.org/volatile/2015-04-17-VjBkc8DWV8c/list
Discuss :)