Oberheim under Gibson has never made a synth that sounds like an Oberheim. You can get those elsewhere, though: a great analog polysynth, the OB-6, co-designed by Dave Smith (Prophet 5, etc.) & Tom Oberheim and made by Smith's company; and various versions of the original Oberheim SEM (Synth Expander Module) made & sold by Tom Oberheim himself.

If Yamaha does acquire the Oberheim name it won't surprise me if they turn around and give it back to Tom. I strongly doubt they have any interest in treading on Oberheim territory.