彼のビジネスプランは立派だけど、勘定あって銭足らず、という気もするけどね。

tbd

His business plan looks good on paper but I get the feeling it would never work in practice.

荒唐無稽と皆に言われた彼のビジネスプランだけど、今となっては我々の不明を恥じるしかないのかね。

tbd

Every one of us who ridiculed his business plan as a bunch of hokum should be embarrassed we did.

孤軍奮闘したけれど、衆寡敵せず、彼のビジネスプランは受け入れられなかったよ。

tbd

He put up a brave and lone struggle, but up against such heavy odds he couldn't get his business plan accepted.

君の夢一杯のビジネスプラン、絵に描いた餅にならんことを切に望むよ。

tbd

This business plan of yours seems almost too optimistic. All I can say is I hope it's more than just wishful thinking.