Wino said
However, on a business case basis there is no way Airbus can launch a competitor because it would be in the position of not only competeing with the 7e7 but also competing with itself (the 330/340) and killing those aircraft before they had paid for themselves (again something no fiscally responsible corporation could do).
In my humble opinion, what Wino said is correct.
Any new Airbus aircraft competing with 7E7 will end A340-300 programme. A340-300 will have two Airbus competitors (the new aircraft and the A340-500). The problem is that A340-500 has a tough competitor now 777-200LR plus 7E7-8LR in the long term.
If Airbus launches a 7E7 competitor based on A330 then A340-300 and A330 classics will see the end.