The first question is what holes exist in their lineup? None, really. And the next question is where do their offerings fall short of what Boeing has to offer? And that is where it gets interesting. The first obvious shortfall is the A330neo is obviously inferior to the 787, and the A350 is bigger and more expensive. There would be room for a CFRP replacement for the A330, which would probably end up being pretty much a direct competitor to the 787, as it would be make it significantly smaller and keep it a twin aisle. It is clear that airlines cannot effectively sell passenger comfort, so if you design it for 8 abreast, as Boeing did with the 787 airlines will use it as 9 abreast. And if you duplicate the A330 cross section you will lose efficiency against the 787, unless airlines squeeze 9 seats in that, as some are doing. And as this will steal A350 sales and have a very hard time competing on price against the 787, I do not see it happening. So the most likely is an A320/A321 replacement in response to Boeing launching a 737 replacement, which is a ways away, because it is really awaiting a technology advance that will make it worthwhile.
For what its worth I am not as bearish on the A330NEO as a lot of people seem to be, although relative to its immediate competitor from Boeing it has to be one of the weaker offerings in the Airbus line up. But I think we will see sales strengthen as it matures.
Any issue the A350 has in terms of cost will disappear as it reaches maturity and full output, especially if the 787 retrenches slightly back from 14 per month to a more sustainable 10 or 12.
I think the A330NEO's future is closely tied to if the 797 launches, and if it is successful.
Whilst it is clear that Airbus can do "things" with the A32X, they may elect to pull the trigger on an A330 replacement which as you say, is slightly smaller and lighter to a) better align to the 787 in terms of appeal, and b) limit the 797 from above.
As the question was "all new programme" I don't see the A350 going away or being replaced. It will clearly get developed.
The A220 is new anyway, and bound for success
The interesting question is the A320. It is not new by any means, but with such a large backlog, and in such a strong position in its niche its hard to see a reason for Airbus to pull the trigger anytime soon. It will have to be being threatened first in my opinion.
The 797 is not a threat to it, but a Boeing NSA would be.
Conclusion - whatever we might like to see from Airbus as an all new programme, they have put the ball in Boeing's court to launch either the 797 or NSA before they respond