Given the length of time necessary to do the hardware and software engineering required to be a credible player in today's smartphone market, I don't think they can do it.
Simply put, RIM sat out two generations on smartphone development, resting on their laurels in the belief that their unique value proposition (ie. the supposed security and reliability of their private network) was enough to withstand the tsunami of the iPhone and its Android competitors.
The new CEO of RIM has stated his intention to focus on the "enterprise" market. This is a mistake: "Enterprise Support" is a feature, not a product. The sort of corporate MIS buyers who used to specify Blackberry have either been outvoted by their corporate peers, or they have needs that are no longer uniquely or defensively answered by RIM.
If RIM had the deep pockets (and patience) of Microsoft, or the massive handheld business of Nokia, they might be able to hang on long enough. But they don't. At this juncture it makes most sense for them to dispose of whatever assets they still have (ie. patents, their global telecommunications network, etc.) while they still have some value.