If Trump wanted this to be an issue in this campaign, he would have brought it up. I think he's said nothing on the subject since 2014. The way I see it, his reason for saying "Obama was born in the US, period" was to avoid the question for now, and to put the issue on Hillary and the press.
I believe that Trump's statement on this is about as sincere as his endorsement of Ryan and McCain. He's learning the political ropes very quickly!
The most amazing thing I heard this morning was when Kellyanne Conway was slamming the media for focusing on this with everything else that was going on and Jake Tapper actually replied, “we, (the press), would be remiss if we let this go”.