I am going to ignore your snide description of play streets as a government program.
My old block in Brooklyn was a play street. It was an awesome resource. Ours was run by the PAL, and they brought games, balls, tables, and COUNSELORS (it might have been part of Summer Youth, I'm not sure.) They opened a hydrant, and kids LOVED it. I'm glad we're getting it here, kids need it.
The streets are obviously not going to be so densely packed that people can't bike on them.