I suspect that his 80's 90's and 00's output would have resembled super slick ELO type offerings.
He doesn't seem nearly aged enough.
He'd have come full circle past humble baggism and be wearing designer bespoke suits a la Clapton. Moving the "what would he be like@ subject one step further, Unfortunately, I don't think we have missed 30 years of groundbreaking Lennon artistry.
I suspect that his 80's 90's and 00's output would have resembled super slick ELO type offerings. Also we would have had a Beatles reunion by now that would have hurt their legacy.