Why would anyone think NISA would start doing Agarest? By all accounts, Agarest 360 version was reasonably successful despite the 360 , generally speaking, catering to a sports/fps/action demographic. No reason to think Aksys would not want to do the subsequent titles.
Idea Factory would have to snub Aksys, and considering the overall quality of both the localization and the limited edition swag (and resulting publicity) - that is also extremely unlikely.
The only questions to this equation that remained after a month of sales were : did IF continue doing builds for x360 while making subsequent Agarest games, and will Aksys be allowed to also sell a disc based version for PS3?
I am betting yes on the first, and have absolutely no idea on the second.