(This story appears in today’s edition of USA TODAY .) The best news for UFC featherweight champion Jose Aldo might be that Anderson Silva can’t keep fighting forever. Brazil’s most famous fighter eventually has to retire, and when he does it could be Aldo (23-1 MMA, 5-0 UFC) who fills his shoes. Regardless of whether Silva (33-5 MMA, 16-1 UFC) regains his UFC middleweight title when he has a rematch with new champ Chris Weidman at the end of the year, Brazil’s king of MMA superstardom is closing in on 40. Aldo is 26, and in excellent position to assume the throne once Silva’s fighting days are done. That’s the hope, anyway, both for Aldo and for the UFC. After another successful title defense at UFC 163 in Rio de Janeiro, however, it’s tough to tell whether Aldo can inspire the same fierce passion in one of the UFC’s key markets. In 2011, when Silva led the charge for the UFC’s first Brazilian event in more than a decade, tickets sold out in less than two hours. The return to the same venue two years later revealed clumps of empty seats on the pay-per-view broadcast, with UFC executive Marshall Zelaznik telling USA TODAY Sports/MMAjunkie.com this latest event was probably within 1,200-1,300 seats of a sellout