Mayor Bill de Blasio and local politicians rode on the newly extended No. 7 subway line to W. 34th St. and 11th Ave. Friday for the ribbon-cutting at the new Hudson Yards stop. Outside the terminus, straphangers can enjoy a new system of tree-lined parks and boulevards. The new station — the city’s first in 25 years — is expected to bring 32,000 riders a day to and from the developing neighborhood, helping fuel Hudson Yards’ growth. Another station potentially could be added to the line in the future at W. 41st St. and Tenth Ave., if there is money for it.