Wow!! Did you see the announcement today that the Exchange and Real Time Collaboration (RTC) Groups were combined to form the Unified Communications Group (UCG)? If not, you can read about it here.
Before you send me a blast of emails, I don't know if this means LCS and Exchange will be a "single" product again. I don't see this happening based on what I've seen and what I know. Keep in mind that this news concerns the two business units being combined into one from a business management perspective - not that the two products are becoming one.
However, who can say what will happen 5 years from now or 10 years from now. Heck, who can say what will happen next month? If you want my opinion, I doubt the two products will become merged into one. And if you didn't want my opinion, too bad - you got it anyways! :-)