As the title suggests, are ground aircraft being added? Absolutely nothing said by WG has suggests this to be the case, however, in 0.5.11, along with the British cruisers, obviously, the British float planes were added to the client. (Divided into folders featuring fighters and scouts)
However, I only discovered now that amongst the british aircraft added, within the British Torpedo bomber file folder, (which in itself is surprising that folder exists, as that folder should not exist until british CVs are added) there is the Avro Lancaster. I have done a good look over the texture file, and there is no doubt that it is the correct aircraft, and it is not some kind of seaplane variant of the aircraft, it has wheels and all for landing, and no evidence of sea floats.
To those of you who are not familiar with aircraft in general, the Avro Lancaster was the main offensive bombing aircraft of the Royal Air Force (RAF), ofwhich over 7,000 of these bombers were built. I have not found anything in regards to their ever being a seaplane/flying boat variant being built.
Now there is the possibility that this aircraft would be part of a map enviroment, and not something players control or interact with, however, as I understand it, such aircraft are not stored within the nations, and their files are stored with the maps they appear on. Unlike this Avro Lancaster whose files are very clearly inside the british nation file folder.
This leaves one other likely possibility, and that is Bastion game mode, as the pieces that make up the fortresses are also stored within the nation files. So we could have AI aircraft bombing targets.