I can see why J2 might be motivated to switch from Boeing to Airbus with crew savings from mixed fleet operation 757/737/8 but that would require a fleet plan for A319/320 -A330 doable and its where Titan seem to be heading, but mail is still a nice little earner, are there any converted Airbus narrow body freighters?
There is now a steady supply of mid life 738's coming to the market and whilst not new, neither are the costs that go with them.
If they introduced the A330 then that would be a huge leap on the 757 and you need to use the range LBA -TFS -LBA or AGP wouldn't make sense, you couldn't fill it on the number of occasion you would need to do to cover the costs, its a long-haul aircraft, it hasn't really worked for Air Berlin, buy a couple of 330 on the used market and get it wrong and it could easily destroy J2 profitability, look at the damage that the introduction of brand new 787's have done to Norwegians profitability and they have a feeder network and huge market presence in their home market of Scandinavia.
Titan are a very different business and don't need to fly their aircraft day in day out they don't have to fill aircraft or profitably sell seats , ACIM is their business and they know it well.
So unless there is news to the contrary i don't see it, if they go with the A330 it will please spotters, not accountants or shareholders, if its about driving J2Holidays.com, then they could do a lot worse than buying long haul capacity from other operators or dedicated charters, if its good enough for Tui & Thomas Cook to use 3rd party airlines then it must make sense for J2