Is it possible to perform a 1g barrel roll in an airliner? Possibly. If the load on the airframe is kept to one positive g, it should be possible. Bob Hoover might have tried it if given the chance. Boeing lead test pilot Tex Johnson did try it at least once on a demonstration flight.
Is it likely to ever happen (again)? No. No owner/operator would allow it. Then, there is the requirement for an aircraft to be certified to perform aerobatics per 14 CFR Part 23.2005. Which no Virgin Atlantic airliner is. I don’t know of any modern type certificated airliner that is certified for aerobatics.
Is this meme a fake? Yes.