Overbaking a cheesecake usually results in it cracking on top and a texture that is slightly drier and more set up. But honestly, a cracked cheesecake isn't the worst thing in the world. It will still taste delicious and you can always strategically cover it up with your chocolate ganache, well placed chocolate shavings, or fresh fruit and hardly anybody will be the wiser. Unless you REALLY overbake it by like, a lot.