Despite the hype, tablets are still most accurately described as a ‘niche‘ market. But that market is expected to grow really, really fast.

That’s according to a study (PDF) conducted by the Online Publishers Association (OPA) and Frank N. Magid Associates, which sees 54m Americans owning or using tablets by early 2012, up from 28m today.

Obviously, that’s good news for Apple, which currently dominates the market with the iPad. But it could also be good news for capable publishers with strong multichannel strategies.

In its survey of nearly 2,500 people, the OPA found that 87% of tablet users use their tablets to access content, making consumption of content and information the “dominant activity” for tablets.

Perhaps more important: of the 93% of tablet owners have downloaded apps, 79% of them have paid for an app, and 26% of all app downloads are paid.

That doesn’t mean that tablets are a paid content panacea, however. According to the OPA, “Consumers want bundled content and payment options for paid content on their tablets, and they prefer a variety of retail channels to buy tablet apps“.

In other words, consumers may not think of the App Store as the be all and end all of tablet content discovery and commerce.

That may provide some validation for the model the Financial Times is employing. The FT, of course, is, for the time being, circumventing the App Store so that it can deliver a true multichannel offering that doesn’t require Steve Jobs to play the role of gatekeeper.

Yet at the same time, we see strategic stupidity on the part of some publishers like the New York Post, which is trying to force consumers using Safari on the iPad to download its app instead.

At the end of the day, there are plenty of reasons for publishers to be hopeful. The tablet population is growing, and as the OPA survey also shows, its demographics are very attractive. But to cash in, publishers will need to have quality content, priced right, and distributed through the right channels. Tablets alone won’t put those in place for them.