Ben Wood, head of research at telecom analysts CCS Insight, thinks WhatsApp could be a $1 billion-plus takeover target.
"Someone could decide to take them out of the market, like Facebook, because they want everyone to use Facebook Chat, or Microsoft to protect its Skype franchise," he said.
"Or alternatively, someone like Yahoo could say this is a platform that gets us engagement with another channel."
WhatsApp did not comment on its future strategy.
BlackBerry established itself by being seen in the hands of lawyers, bankers and politicians and became the smartphone of choice for British teenagers and young adults.
It held 35 percent of the British market for 16-24 year olds early in 2012, according to Ofcom data, beating Apple and Android, but fell to 17 percent a year later while Apple and Android had 40 percent and 35 percent respectively.
Facing the loss of a key demographic, BlackBerry announced it would make BBM available for Android and iPhone, but, in another stumble, the roll out was paused on Saturday after an unreleased version of the BBM for Android app was posted online.
"Everyone has moved on from BBM. iPhones are more reliable and you usually get unlimited texts with an iPhone contract. The screens are bigger, the apps are better, so why would you want a Blackberry?" said 17-year-old London student Freya Bowen.
CCS Insight's Wood, however, said BBM could be one of BlackBerry's most valuable assets if it can keep the loyalty of its remaining customers and add more on other platforms.
"If BlackBerry really deliver a slick application, that draws on the heritage where all the people that used to love BBM can get it again, and they get all of the immediacy and the privacy, (...) then there is a chance they could ramp it up to 200-250 million users and get up there with WhatsApp," he said.
Kik, created and launched in October 2010 by a team of students at Canada's Waterloo University and located next to BlackBerry's HQ campus in Canada, now has 50 million users.
Kik founder and CEO Tim Livingston said he expected one of the big five cross-platform messaging services