Instagram may have surpassed 27 million users for its iPhone app, but imagine what that number could’ve been if Android downloads were included. At SXSW this year Instagram co-founder Kevin Systrom showed off an Android version of the app, finally proving what’s long been rumored: Instagram will hit Android “very soon.” And while Instagram will lose an air of exclusivity once it expands its reach beyond a single device, that’s not necessarily a bad thing. With Android being the top smartphone OS in the world, Instagram will really reap the benefits of launching an Android app.

Since Android toppled iOS as the number one mobile platform, developers quickly recognized the potential of an open market with a broad user base. Android provides an alternative to the closed iOS ecosystem with a range of partners to widen the pool of consumers owning smartphones. As early as last summer we saw developers seeking a cross-platform strategy emerging, where consumers became the central target, not the OS. Developers go where the users are, and that means launching an app on the iPhone, Android, Windows Phone and BlackBerry. Instagram’s significantly limited in its reach, even lacking an iPad app for iOS users or a viable website for online photo management or extended sharing capabilities.

Instagram on Android is about more than numbers

But launching an Android app in addition to an iOS app is about more than just numbers. As I’ve mentioned before, the battle between these top mobile platforms is now about their ecosystem as a whole, and Google’s extended family will amplify Android’s market. Instagram, a highly social application, can take advantage of Google+, a growing influence in social search and content distribution. Even a web app for Google Chrome could have an impact on Instagram’s long term success. Google was named a top U.S. brand last year, and as Google consolidates its ecosystem around content, applications and services, the search company is clearly making a play (pun intended) at better connecting developers and consumers.

The perks are extensive for Instagram, which will need to implement a broader scheme to profit from its social-centric business model. Rumored to have a valuation of $500 million, Instagram seems destined for success as a mobile institution, and Android plays a big role in the long-term potential, even before the Instagram app is launched. Rolling out apps beyond the iPhone will grow Instagram’s ability to become a platform all its own, appealing to marketers, other developers and, most importantly, consumers.