I know there has been some statements (speculation?) on the internet that the raw material problem only affected the 120 version (backing paper problem).
I don't know the source, and I don't know whether there has been an official statement from Fujifilm about that.
All I can say is the information I got at the Fujifilm booth from their responsible Product-& Key Account Manager, Photo Imaging Products Mr Boll:
He told me there was a problem with one raw material, which caused the production stop. When he told me that, he at least didn't referred it only to 120. It sounded like being a general emulsion problem affecting all formats. He said Fujifilm did some R&D to replace the problematic material and they have been successful, the problem is solved.
But we didn't go in further details about this topic (raw material problem) in our talk.
Neopan 400 (135) was visible both in the showcase and the brochures at their booth.
At Photokina some big European film distributors told me that they also have received direct information from Fujifilm, that Neopan 400 (135) will be available again this autumn.
All the information I have got at Photokina I've told you. Please have a look at my postings at the beginning on the first page.
I think it makes no sense to go deep in further speculation.
Those of you who like Neopan 400 can relax and be happy. Personally I prefer the Ilford and Kodak films in this ISO 400/27° BW segment, but I feel with you Neopan 400 fans and share your delight about the positive news.