In what way is it not? The groups are trying to be very cautious with their words, but read between the lines. From a study,

However, when the E484K mutation was added, substantially higher levels of antibody were required – on average this mutation required an almost ten-fold increase in the concentration of serum antibody for neutralisation when compared to the strain circulating prior to B.1.1.7.

In the previous paragraphs, the B117 variant without E484K only required a 2x increase, and doctors suggested the vaccine will be moderately effective against it. A 10x increase? It'll require a new vaccine. Another outbreak depends on if we can rush out a modified vaccine faster than it can spread. Based on our current rollout, I'm gonna have to say it ain't happening