I don’t think that the A380 was a mistake. It killed the market for B747-400 and forced Boeing to build the B747-8i. This aircraft doesn’t sell so well and now is under attack from below by the B777-X9.
Airbus didn’t benefit directly from B787 battery problems. Airbus used the same lithium batteries on A380 without problems. Airbus switched to old NiCd batteries not due to safety reasons but due to avoid problems with any upcoming certification requirements.
Airbus did sell more A330 after the B787 program was started then before. To keep pressure on Boeing Airbus could start an A330NEO in a few years. A350 is larger than A330. There might be enough costumers for A330-200 with new engines.
There aren’t going to be new engines for the A330. Aint nobody got time for that.
With Max effort, the earliest a next gen engine would be available would be around 2019 and by then, the A330 will be pretty long in the tooth.
GE won’t let the GP7200 go on other airframes that compete against GE engines, Rolls is tapped out and Pratt has at least 4 new engines in the fire, none of which are easily scalable to 70K thrust.
Already having 3 engine choices has allowed the A330 last a few years longer than natural as it was a lack of choices that killed the A340 (basically the same airframe).