If the language uses curly braces to define blocks, it's easier: ciB. Parentheses are easy as well: cib. Otherwise, I'm not sure there's a good solution currently. You can substitute by indentation with a plugin (https://github.com/kana/vim-textobj-indent/blob/master/doc/t...). For Lua, I usually do c/end<enter>.

I believe this is an area where treesitter can help, so I'm looking forward to Neovim's integration.