Might it happen. Sure. Probability <25% in my opinion.
Would it mean the end of the ONS line? I doubt it. Probability <25% - given the above hypothetical comes to pass - IMO.
Has Cisco ever spun off a major product line/business? Not in my memory.
Is the ONS line still being enhanced? Yes - look at the hardware and software releases: http://www.cisco.com/en/US/products/hw/optical/ps2006/prod_release_notes_list.html
Just my 2 cents....
