I'd like to view this as positive. Instead I see it as another dropped football.
Let's recall that in 1988 the SSTO was proposed to be in test phase by 1990. In 1990 it was supposed to be in test phase by 1993. In 1997 it was supposed to be in test phase by 2000. Now they are saying "something???" will be test phase by something like 4.5 years from now.
Frankly I don't think NASA has the capability to drive this program. They should set up a consortium of Lockheed, Boeing and other corporations to drive a SSTO development design and construction phase, then get out of the way. Other than that, NASA is just screwing around one more time. And that is pathetic.