Producers of Broadway tuner “Evita” are betting the show can live on even without the big B.O. draw of topliner Ricky Martin, announcing the musical will continue an open-ended run once its trio of leads departs in January.Martin’s name on the marquee has been a major factor in the musical’s strong sales, which regularly top $1 million per week; sales have plummeted notably in Martin’s temporary absence. He’ll stick with the show through Jan. 26, along with Elena Roger and Michael Cerveris, who will also exit on that day. With Martin’s end date now in sight, the onus is on producers to pull together a new cast that can feasibly sustain the show. No names have yet been set. Helmed by Michael Grandage and choreographed by Rob Ashford, “Evita” quickly became one of Broadway’s big sellers when it opened in the spring, pulling in theatergoers drawn from Martin’s international fanbase. Since beginning previews in March, the show has rung up some $43.7 million, logging a bit more than $1 million in the Thanksgiving frame. Produced by Hal Luftig and Scott Sanders, “Evita” will likely get a B.O. boost over the year-end holidays (along with the rest of the Rialto); it remains to be seen whether the presence of Martin and his co-stars can keep sales equally lofty over the traditionally fallow weeks of January.