It wasn’t a complete shock this morning when BlackBerry CEO Thorsten Heins announced that the popular BlackBerry Messenger, one of the few remaining apps chaining BlackBerry users to the platform, would be coming to iPhone and Android in the form of a free app this summer.

"It’s been a long time coming," said Ted Livingston, CEO of the free multimedia messenger app Kik. "We heard that the project had started and stopped, started and stopped."

Former co-CEO Jim Balsillie reportedly pushed the company toward a cross-platform strategy before he stepped down in January 2012. The idea was scuttled in part by Heins, who rejected the idea in favor of pushing a lineup of new BlackBerry 10 phones, Reuters reported.

BlackBerry may have been inspired by the boom in messenger apps

BlackBerry may have been inspired by the boom in cross-platform messenger apps such as Kik, which is adding 200,000 new users a day, and WhatsApp, which has more users than Twitter. It may have been spurred to action by rumors of Google’s messenger Babel, which could be announced at tomorrow’s I/O event. Elsewhere in the messaging industry, Microsoft bought Skype, Facebook has Facebook Messenger and Facebook Home with Chat Heads, and Viber just expanded to desktop.

"It’s becoming very clear to everybody in tech that messaging is the killer app in mobile," Livingston said. "If you don’t have a messaging play, you’re not going to have a shot at being the center of this mobile era of computing."

Or it may be, as the company said, that solid sales and a return to slim profitability have given BlackBerry the "confidence" to start offering one of its most compelling services to users without requiring them to buy a BlackBerry phone.

"Users have been asking for it for years, it's not a new conversation," Andrew Bocking, BlackBerry executive vice president of software product management and ecosystem, said today. "Now is the right time. We've seen growing traction and interest in other messaging solutions. We feel that BBM offers the best experience to do that, so making it available on other platforms will address those needs."

"Users have been asking for it for years."

Is now the right time? There are so many competing messenger apps on the market that it may be tough to get users to pick up BBM. And if opening BlackBerry Messenger up to users on other platforms was such an obvious move, why didn’t BlackBerry do it years ago?

"They just had to reach some sort of a tipping point," Jan Dawson, head telecom analyst at Ovum, told The Verge. He suspects the move was prompted by the recent decline in the BlackBerry subscriber base combined with the success of independent messaging apps like WhatsApp.

"Many BlackBerry users are seeing their friends shift to other platforms and away from BBM, so the value of BBM has been diminishing," he said. "If they wait too much longer, it won't be worth doing anymore. They want to get in there while there is still time to build on the 60 million users they have, when everybody hasn’t deserted them."

It's been widely reported that BlackBerry is losing subscribers, although the company says its current 60 million base of BBM users is the largest it's ever been. Regardless, BlackBerry is making a larger play. "The first point is to grow an audience and to grow engagement with that audience. Once we have an audience established, we will have opportunities to monetize it," said David Proulx, lead of BBM for Android and senior director of consumer service business.

"If they wait too much longer, it wouldn’t be worth doing anymore."

BlackBerry Messenger is widely regarded as an excellent service that was far ahead of its time. It started as a secure, rich text messaging service that incorporated longer texts, emoticons, and pictures, all at the speed of an instant messenger. It caught on big in the finance world, where every Wall Street firm required its employees to use BlackBerry, and soon it became its own kind of social network. BlackBerry Messenger was the first service to incorporate read receipts, and although it never gets as much attention as Twitter, it was used by young protest organizers in the UK. BlackBerry Messenger even allows for face-to-face video chat. It’s every other messenger in one well-designed app — except it's only been available on BlackBerry, a platform that is quickly losing traction.

But at some point, mobile messaging took off while BBM was left behind, siloed in a BlackBerry world. BBM was a huge early success for BlackBerry, following email as the company’s killer app. BlackBerry was caught flatfooted by the iPhone, and the same thing happened to BBM with the latest generation of messaging apps. Just as BlackBerry 10 was a last-ditch effort to stay relevant, BBM's move to cross-platform is as necessary as it is late.