Beginning in 2015, Darlington Raceway became home to NASCAR’s throwback weekend with teams honoring iconic paint schemes of the past. And for the past nine years, we’ve seen many great looks make a return, from Richard Petty’s Petty Blue/STP Day-Glo Red to Jeff Gordon’s Rainbow-Colored ride and everything else in between. But when it comes to the future of throwback weekend at Darlington, Denny Hamlin isn’t convinced it’ll have staying power much longer. Speaking on his “Actions Detrimental” podcast, Hamlin said he wouldn’t be surprised if this year was the final throwback weekend at Darlingto…