I spent months frustrated by Skitch breaking, including reading through all these posts, hoping for a solution.
I recently stumbled across a great (and as far as I can tell, free) Skitch alternative. I downloaded it and have been using it for a few days, it's a perfect replacement.
It's called "Annotate App" by Linebreak. Link to the mac app store, if the forum will let me: https://itunes.apple.com/us/app/annotate-capture-and-share/id918207447?mt=12
I was shocked at how hard it was to find this app, given how perfectly it replaces Skitch. That's the only reason I CREATED AN ACCOUNT ON THIS FORUM to post this message.
Good luck, everyone. I hope Annotate does what you need.