The witnesses to Tony's death will lie to provide Chino with an alibi as part of their efforts to reconcile.
Maria is pregnant from sleeping with Tony before his death.
A month or two afterwards, she'll realize she's late and give birth to a son, who she'll name Anton Bernardo. Raising him as a single mother, the Jets and the Sharks will help, and move toward reconciliation.- Why not go further? After he grows up with a mother and, like, seven or so father figures (who, of course, all went straight for little Tony's/Bernado's sake) and who include a fully accepted "Uncle Anybodys" they all chip in to send him to a good university and he goes into politics and spends his career working towards friendly inter-racial relationships?