Buenos Dias a ti
My only guess is that either both
airlines were experiencing very poor/drop in pax or cargo loads, or pax loads were good, but yields were poor.
That the decisions by either airline to drop routes between the UK & Cuba were unrelated to each other.
Cubana may have been motivated to drop the route, as it may have experienced capacity problems (requiring the a/c to operate other services, when it was enroute to/from the UK).
Or that Cubana could not compete with BA, and decided to drop the route before they knew BA would drop it too.
The other alternative has already been mentioned by a few people already; that BA's decision to axe the route was due to poor loads in it's premium cabins (Club World, in this case), and that this decision was made irrespective of whatever Cubana had decided/not decided to do with the same route.
As it stands, I beleive a few UK Charter airlines do still fly to Cuba, although I beleive they fly into Varadero, rather than Havana.
Buenos Dias to you too!
As far as I know, BA are now operating the B777 to EZE, non-stop from LGW. I beleive BA plan to increase frequencies on that route to 6x weekly.
If the route continues to become popular, BA may decide to move the service to Heathrow (as has happened with services to Brazil).
The a/c is operated in FJY configuration.