my iphone4s was stolen and i get email from apple they erased do you think the theif can use still my iphone

my iphone4s was stolen then i go to my icould account and make lostmode then erased. i get email from apple they erased that is good to hear that but do you think can he use my phone and make jailbreak. if it is yes i have my device nr and when i buy and serial nr and i want make him to black screem or useless phone