There'll still be loads of tickets left after the presales so I wouldn't worry, I can't imagine loads of people signed to this 02 subcription are coincidently X fans, and I can't imagine a huge load of people who've never heard of the band saying "well I never heard of this band, but since I have the chance to get pre sale tickets I'll check them out", I think pretty much all the seats will still be available by the time normal ticket sales start on Friday.
Now to wait and see wether this concert is even true or not.