As a Southern modeller we've been spoiled for small tank engines of late. The Dock tank, Beattie, O2 and the announced Dapol B4 and Hornby's H class.
I think if I was Modelrail I'd be looking to another region for a suitable candidate for the next project.
I also think that a national publication wouldn't want to be seen as to southern centric.
From a personal point of view my wallet could well do with a brief period of respite what with all the other Southern region models to come, as built MN's, birdcage stock, gate stock etc
Atb
Nik