Thoughts on the proposed film.
I watched "Star Blazers" as a kid and remembering loving it. As I have gotten older I regularly return to the idea of the show which I think would make a good movie or a good live action TV series (lets face it, Crusade was a knock-off of Star Blazers.)
I read the original live-action screenplay done by T. Murphy back in the 90's and it was a suitable space opera tale. My problem with it was they wrapped everything up in one movie.
To do "Star Blazers" correctly, I think they would need to do a trilogy of films.
The first film would establish how screwed Earth and humanity are, establish the main characters, have help arrive from planet Iscandar, build/unveil the Argo, get them on their way, have them visit a planet or two and have them face a challenge (space battle) that they overcome and let everyone start to feel that there is hope again.
The second film would have the Argo facing more challenges, being involved in more battles (I am thinking space battle and ground assault on some alien fortress), suffer some terrible losses (those who saw the series know what I am talking about), let things appear bleak and then get to Iscandar and get what they need to save Earth. Then have all hell breaks loose as they have to fight to escape. Have them just get away and on their way back home after taking a severe pounding.
The third film would be the return trip and having to face their enemy in a giant final showdown with some other subplots worked through, people admitting they love one another and so on. The Argo is victorious, show them saving Earth, it is the dawn of a new day and an unlimited future...and we fade out.
The End.
Like Lord of the Rings, this is a quest story told in a sci-fi universe. You need at least three films to tell it correctly.