It depends on what you mean by 're-form'. Pink Floyd consists of David Gilmour, Nick Mason, and Richard Wright, with various musicians brought in to assist in the studio or on stage. The line-up has remained static since the acrimonious split with Roger Waters, and a legal tussle over the rights to the band name, which Waters lost. It is unlikely that Roger Waters would wish, and certainly has no need, to join his erstwhile colleagues on stage or on record. The band continues in hibernation, and may or may not reconvene to record and tour again, depending on how they all feel about it. As a major Floyd fan - I've seen them four times with Roger Waters, and three times without, I have to say that his presence, although nice for nostalgia, is far from essential in an artistic sense.