I know Konami's Suikoden box was put on hold (possibly canceled). But I don't think S-E announces this stuff lightly.
It is the 20th anniv of the Mana series, after all.
Based on the contents, "physical artifact" fans should be pleased to note that Children of Mana was previously a digital-only soundtrack release. This will put it in physical form. Plus, unlike the SaGa box, this one picks up on two arranged albums as well (which is really the only arrangements, outside select arrangements on drammatica or the "SQ" albums).
I'm totally saving up money for this, and if I'm still employed come September, I'm-a order it. :)