After ditching The Big Bang Theory in its dying days, Jim Parsons is hinting at a major comeback as Sheldon Cooper in a possible spin-off. Producers of the hit sitcom are working on a third spin-off, following the recently concluded Young Sheldon and the new series Georgie & Mandy’s First Marriage, RadarOnline.com can reveal. The yet-to-be-named spin-off has recently added Brian Posehn, Kevin Sussman, and Lauren Lapkus to the cast, all of whom had recurring roles on the original Big Bang Theory. Though deals have yet to be made with the main stars, including Kaley Cuoco and Johnny Galecki, Par…