Sublime text is one of the best pieces of software ever written and is regularly updated. Stop being a cheapskate and just pay for it if it is valuable. Making it free and open source is a bizarre thing to ask.
Being a long-lasting supporter of open source software, I wholeheartedly agree with you. There are many commercial software masterpieces (Sublime Text, Bitwig, Houdini among others) that would never (or at least in the foreseeable future) achieve that level of perfection without commercial support of the developers, allowing them to focus on their product.
While I'd like the ST to become open source (although I doubt it would improve the program significantly), it should keep its commercial license. I'll happily renew when my v3 license expires.