Will lost mode work without a sim card?

My iphone got left in a taxi, and the taxi driver has said he didn't find it when he looked. Either he geninely didn't find it (he's overlooking it, I know I had it in the taxi and didn't have it after i left the taxi) or he's decided to keep it. My problem is that because I was traveling abroad I happened to not have the sim card in it. So it only works on my wifi network and maybe some public network or something that i've used previously. So it will never show up on find my iphone again. I put the lost mode on because I wanted it to block someone from resetting and selling it, but will that stop someone from doing that if they never connect to a wifi network until AFTER they reset it?