All Japanese All the Time is a site that claims that with a significant amount of work, though doing the things you enjoy, you can become fluent in Japanese without ever taking a Japanese language class. The site itself is pretty inspiring, and certainly worth a look, but there are some points to keep in mind before embarking on the approach outlined on the site.
First, the input before output principle is solid. This is definitely something you can and should apply to your studies.
On the other hand, the idea that you can read only what you enjoy and become fluent in Japanese-- well, it depends on what you mean by fluency. If you want to navigate a business situation well, you're going to need to know not just about business, but about politeness levels in speech. Since these vary in Japanese depending on your social position, they're hard to simply absorb and emulate from others, as you have to already know people's social positions before making the decisions.
Third, I don't recommend Heisig's Remembering the Kanji. I think Kanji in Context is a much faster, easier approach to fluency.