NASCAR, the governing body of stock car racing in the U.S., dumped North Wilkesboro Speedway into history’s dustbin in 1996 when it took away the North Carolina track’s two lucrative “Cup” races. But apart from the track, it also left behind bitter fans, its grassroots, as it chased the dollar bonanza offered by bigger markets. More than two decades later, experts are cautioning that Major League Baseball might be poised to make the same mistake.