How is it a threat to the mobile market when BT have (effectively) no mobile service?
Don't get me wrong, I'm not boosting for BT or EE here, I just don't see the threat (in the mobile market).
Now, 3 eating O2 is a definite threat to competition. Alas, I do hope that one goes ahead but only because I'm with O2 and Three's network is far better in my home area (in that Three's actually works and O2's doesn't. At all. Damn them and their shitty TuGo app that also doesn't work).