We know Jenny is in the pipeline. Nick was assuring India Fisher for years about the Charlotte Pollard spin-off, so it's possible Nick approached Georgia about the Jenny spin-off (Goorgia's been a few stories over the past five years), she mentioned it to her father Peter Davison, who brought it up at the convention. All that's left is for Big Finish to formally announce it, which will happen when recording is done and when the BBC give the announcement the green light. Like Tales of New Earth it'll need all the help it can get.
At the time of the Radio Times articles it had yet to be recorded, but it was revealed the companion figure would be played by Sean Biggerstaff. I'd like to think that the writer was trying to get some free publicity, but I seriously doubt Big Finish will work with them again.