According to Switch magazine vol.30, Shinbo Akiyuki
has revealed that the anime projects of Nisio Isin
works will continue up to the tenth.
Nisio Isin Anime Project official website
Nisio Isin Anime Projects Announced so far
is not included because Nisio Isin anime projects are run by Kodansha.)
Shinbo said he wanted to produce an original anime written by Nisio Isin as the tenth work.
Source: Scan of Switch