Some things to have into consideration.
YUI has been playing in secret as FLOWER FLOWER for quite some time. (Months)
YUI started this, because, apparently, Sony wouldn't allow her to release the music she wanted to do. As you can conclude from the latest interviews, she had problems with the tie-ups and the way they forced her to change her songs to fit the needs of each client.
Despite the above, she is still on a contract with Sony and Stardust.
Of course Sony wouldn't let het go just like that, and probably they came to an agreement
She has been playing her "new songs" in small venues, testing them with small audiences where many of her friends involved in the music world are present.
The barrier formed by Sony between YUI and her fans is gone for now. YUI's music is being performed in its purest form, directly from YUI to the group of very very lucky fans that have been able to see her in these concerts.
It is still not clear if FLOWER FLOWER is the name of a band. she has indeed played with a band
before, but most of the time she plays alone with her guitar, also as FLOWER FLOWER , so it could be an alias just for her as well.
When is she going to "debut" again is still not decided. But now that this news has been leaked (I thnk this was not YUI's intention just yet) they will have to come up with an official statement sooner or later, because there are too many rumours and faux information piling up, and some fans are already feeling that YUI is going the wrong way, based only in biased opinions.
For the time being I just want to see her new haircut xD